CURTIS TRANSISTOR MOTOR CONTROLLER

Transcription

1 CURTIS TRANSISTOR MOTOR CONTROLLER W40-60XL, B40-60XL [D135]; N30FR [A217]; R30ES [B174]; R30XMS [C174]; R30XMS2 [D174]; W60-80XT [E135]; B60-80XT [B199]; C60-80XT [B199]; W40XT [A218]; W45XT [A215, B215]; T5XT [E142]; W20/30/40XTA [A453]; W20/25/30/40XTC [A454]; W20/30XTR [A455] PART NO SRM 411

2 SAFETY PRECAUTIONS MAINTENANCE AND REPAIR When lifting parts or assemblies, make sure all slings, chains, or cables are correctly fastened, and that the load being lifted is balanced. Make sure the crane, cables, and chains have the capacity to support the weight of the load. Do not lift heavy parts by hand, use a lifting mechanism. Wear safety glasses. DISCONNECT THE BATTERY CONNECTOR before doing any maintenance or repair on electric lift trucks. Disconnect the battery ground cable on internal combustion lift trucks. Always use correct blocks to prevent the unit from rolling or falling. See HOW TO PUT THE LIFT TRUCK ON BLOCKS in the Operating Manual or the Periodic Maintenance section. Keep the unit clean and the working area clean and orderly. Use the correct tools for the job. Keep the tools clean and in good condition. Always use HYSTER APPROVED parts when making repairs. Replacement parts must meet or exceed the specifications of the original equipment manufacturer. Make sure all nuts, bolts, snap rings, and other fastening devices are removed before using force to remove parts. Always fasten a DO NOT OPERATE tag to the controls of the unit when making repairs, or if the unit needs repairs. Be sure to follow the WARNING and CAUTION notes in the instructions. Gasoline, Liquid Petroleum Gas (LPG), Compressed Natural Gas (CNG), and Diesel fuel are flammable. Be sure to follow the necessary safety precautions when handling these fuels and when working on these fuel systems. Batteries generate flammable gas when they are being charged. Keep fire and sparks away from the area. Make sure the area is well ventilated. NOTE: The following symbols and words indicate safety information in this manual: WARNING Indicates a condition that can cause immediate death or injury! CAUTION Indicates a condition that can cause property damage!

3 Curtis Transistor Motor Controller Table of Contents TABLE OF CONTENTS General... 1 Principles of Operation... 2 General... 2 Transistor Motor Controller... 3 Basic Controller Operation... 5 Field Effect Transistor (FET)... 5 Motor Circuit That Operates With Pulses... 5 Induction Current From Motor... 7 Plugging... 8 Control Circuit... 9 Static-Return-To-Off (SRO) Function... 9 Thermal Protection Function Low Voltage Protection Function Current Limit Protection Function Power Circuit Sequence of Operation Key Switch Brake Switch Control Circuit FWD/REV Switch Closed Forward Contactor Energized Gate Pulse to FETs FETs ON for Time of Gate Pulse Gate Pulse Removed Induction Current Flows Through Motor and Flyback Diode Plugging Checks Checking Contactor Coil Checking Transistor Controller Checks With Controller Installed Bench Checks Accelerator Potentiometer Checks and Adjustments Adjustments Plugging Adjustment Acceleration Adjustment Current Limit Adjustment Repairs Contactors Replace Curtis Contactor Parts, Replace GE Contactor Parts, Replace Controller, Replace Accelerator Potentiometer and Control Switches, Replace and Adjust Troubleshooting General General Procedures Fault Procedures HYSTER COMPANY i

4 Table of Contents Curtis Transistor Motor Controller TABLE OF CONTENTS (Continued) This section is for the following models: W40-60XL, B40-60XL [D135]; N30FR [A217]; R30ES [B174]; R30XMS [C174]; R30XMS2 [D174]; W60-80XT [E135]; B60-80XT [B199]; C60-80XT [B199]; W40XT [A218]; W45XT [A215, B215]; T5XT [E142]; W20/30/40XTA [A453]; W20/25/30/40XTC [A454]; W20/30XTR [A455] ii

5 2200 SRM 411 General General This section describes the operation, checks, repairs, and troubleshooting of the Curtis PMC 1204 or 1205 series. It also covers the 1207 series and the new series of the 1243 motor controller. See Figure 1, Figure 2, and Figure 4. This transistor motor controller is used to control the operation of some 24- and 36-volt electric lift trucks. The controllers are made for Hyster Company by a division of Curtis Instruments, Inc. The controller for the traction system uses digital logic. Digital logic uses transistors to operate like very fast switches. The transistors are controlled by electrical gate pulses. Electrical noise is also high voltage pulses caused by momentarily operating other electrical devices. Digital logic cannot understand the difference between control pulses and electrical noise. Filter capacitors are connected between the B+ and B terminals in the controller to prevent electrical noise from entering the logic and causing errors. The logic of the controller also checks the following functions: 1. Checks the temperature and gives both low and high temperature thermal protection to the controller. 2. Electrically checks that an operator follows the correct starting sequence to help prevent unexpected operation. This function has been called Static-Return-To-Off (SRO) in other Hyster motor controller Service Manual sections. 3. Electrically checks the traction circuit for certain malfunctions. This function prevents lift truck operation if a failure is sensed. 4. Checks the current in the motor circuit and automatically decreases the motor voltage to reduce the current and prevent damage. The plugging circuit is also controlled for smoother operation. NOTE: B60-80XT SHOWN. W45XT, W60-80XT, C60-80XT, AND T5XT MODELS SIMILAR. Figure 1. Transistor Controller on Truck (Early Production) 1

6 Principles of Operation 2200 SRM 411 Additional information showing how the motor controller is electrically connected in the lift truck isshowninthesectiondiagrams 8000 SRM 457 for the walkie low lift motorized hand trucks, Diagrams Curtis Transistor 8000 SRM 495 for N30FR units, Diagrams Curtis Transistor 8000 SRM 475 for R30ES units, Diagrams 8000 SRM 653 for the walkie high lift motorized hand trucks, and Diagrams 8000 SRM 923 for the R30XM2/XMA2/XMF2/XMS2 units. NOTE: B60-80XT SHOWN. W40XT, W45XT, W60-80XT, C60-80XT, AND T5XT MODELS SIMILAR. Figure 2. Transistor Controller on Truck (Late Production) Principles of Operation GENERAL Amotorcontroller for an electric lift truck controls the speed of the traction motor by making a variation in the applied voltage. This controller uses solid-state electronic devices to permit efficient control of theappliedvoltage. The motor controller also generates a high current flow in the traction motor while keeping a low current draw from the battery. A battery is less efficient at a high current draw. A battery will not give all of its electrical power at a high current draw. The traction motor is a series wound motor that generates torque. This torque is proportional to the current moving through the motor. The speed of the motor is controlled by the voltage and mechanical load connected to the motor. The motor will accelerate until the mechanical load equals the torque required. If the torque increases, the current and acceleration will increase. The two functions look like a problem of opposite needs. How a solid-state electronic controller balances those needs with efficiency is described in this section. 2

7 2200 SRM 411 Principles of Operation TRANSISTOR MOTOR CONTROLLER The motor controller controls the speed of the traction motor. The direction of rotation of the motor is controlled by the Forward/Reverse switch and contactors. See Figure 3, Figure 4, and Figure 5. The controller is sealed in an aluminum case and has no parts that can be repaired or replaced. The complete unit must be replaced if correct troubleshooting methods show that the unit is damaged. External contactors are used to control the direction of rotation of the traction motor. Contactors are electrical switches that use an electromagnet to operate the power contacts of the switch. A small electric signal is used to energize the electromagnet to close the power contacts and control the large current flow needed for the motor circuit. The electromagnetic field in the coil moves the armature against spring pressure to close the power contacts. When the coil is de-energized, the spring pressure moves the armature and opens the contacts. When a spring holds the contacts of a switch open, the switch is called normally open (NO). If the switch spring holds the contacts of a switch closed, the switch is called normally closed (NC). 1. PMC 2. ELECTRIC BRAKE 3. APS 4. STEERING MOTOR 5. CONTACTOR PANEL 6. HYDRAULIC PUMP MOTOR 7. DRIVE MOTOR Figure 3. Transistor Controller on Truck (New Production) 3

8 Principles of Operation 2200 SRM CONTROLLER 2. LC CONTACTOR 3. POWER FUSE 4. LIFT PUMP CONTACTOR 5. 1A CONTACTOR 6. CONTROL FUSES 7. TIMER 8. FORWARD/REVERSE CONTACTOR Figure 4. Transistor Controller Panel (W/B40-60XL Units) There are two contactors that control the direction of rotation of the traction motor. Each direction contactor has two sets of contacts on the same plunger assembly. Each contactor has a set of NO contacts and a set of NC contacts. When one set of contacts is closed, the other set of contacts must be open. This arrangement prevents the wrong sequence of closed contacts that could cause an open circuit. This arrangement of contactors also permits current flow through the motor field in either direction. See Figure 5 and Figure 6. One set of contacts causes the motor armature to rotate in one direction. The other set of contacts causes the motor armature to rotate in the opposite direction. See Figure 7. Other contactors used for control functions on the lift truck only have one set of contacts because a forward and reverse operation is not required. An example is the hydraulic pump motor contactor. Contactors are used to energize and de-energize motors, but cannot control the speed. The transistor motor controller applies battery voltage in short, fast pulses to a DC motor to control the speed. How this circuit controls the speed of a motor with pulses is described in this section. The direction and speed control operates the FWD/ REV switch to energize the direction contactor. The control also supplies the speed input to the motor controller. 1. BATTERY 2. TRACTION MOTOR ARMATURE 3. TRACTION MOTOR FIELD 4. REVERSE CONTACTOR CONTACTS 5. FORWARD CONTACTOR CONTACTS 6. FETS SWITCH Figure 5. Basic Traction Motor Circuit Figure 6. Current Flow Through Field in FORWARD Direction 4

9 2200 SRM 411 Principles of Operation voltage. See Figure 8. Electricity flows easily from the input to the output. A FET will only permit current flow when there is a positive voltage at the input, a negative voltage at the output AND a positive voltage applied to the gate. A FET will permit electricity to flow from the input to the source as long as there is the signal voltage at the gate. The FETs ON time is the same as the gate pulse ON time as shown in Figure 9. Current flows as shown in Figure 8. The FET stops conducting when the signal voltage is removed from the gate. When FETs are used as a switch: a. The FETs are ON when the electric current flows through them (gate voltage applied). b. The FETs are OFF when the electric current cannot flow through them (no gate voltage). Motor Circuit That Operates With Pulses Figure 7. Current Flow Through Field in REVERSE Direction Basic Controller Operation This transistor motor controller has a power section and a logic section with solid-state electronic circuits that control the operation of a DC motor. The speed of DC motors is controlled by the average applied voltage. The higher the average applied voltage, the faster the motor will rotate. If a switch is put in the traction motor circuit (see Figure 4) and the switch is changed to OFF and ON quickly (see Figure 9) the traction motor will rotate. The speed of rotation increases as the time the switch is ON increases. The speed of rotation will decrease if the ON time decreases. OFF time will increase at the same time. The speed of the motor can be controlled using this principle. This controller uses an electronic device called a Field Effect Transistor (FET) to generate the rapid ON and OFF pulse times. It has no moving parts. The FETs are turned on and off by the logic circuits in the controller to act as the switch. Several power FETs are connected in parallel to carry the necessary motor current. Field Effect Transistor (FET) A FET is a solid-state device that operates like a very fast switch. A FET is a transistor that has an element called a gate. FETs are electronic devices that permit electricity to flow as long as there is a gate A schematic that shows the controller and FETs in a tractioncircuitisshowninfigure8. Whenasignal isappliedtothegateofthefets,thefetsareon and current flows from the battery through the motor. When the gate signal is removed, the FETs are changed to OFF. Thebatteryvoltageisappliedtothemotorinpulses. The pulses of energy through the FETs to the motor are very fast (15,000 on/off cycles per second). The motor cannot follow each pulse, but the motor runs smoothly based on the average voltage generated by the ON and OFF times. The average motor voltage applied to the traction motor is shown in Figure 9. The length of the ON TIME of the pulses changes the average motor voltage. As the ON TIME of each pulse increases (OFF TIME decreases), the average motor voltage increases. This change in the ratio of ON TIME to OFF TIME of the pulses is called pulse width modulation. The control circuit has an oscillator and a pulse width modulator. The oscillator generates a saw tooth waveform at a constant frequency of 15,000 cycles per second (15 khz). The pulse width modulator uses this saw tooth waveform to generate a pulse output that can be smoothly changed from a full ON to a full OFF condition. This pulse output is used by the gate driver circuit for the high pulse currents needed to turn the FETs ON and OFF. Thepulse width modulator controls the ON and OFF times of thefetsthroughthegatedriver. TheratioofON TIME to OFF TIME sets the average motor voltage and the motor speed. 5

10 Principles of Operation 2200 SRM 411 Legend for Figure 8 1. BATTERY 2. TRACTION MOTOR 3. GATE DRIVE 4. FET INPUT (+) 5. FETOUTPUT( ) 6. FET GATE (+) 7. POSITIVE SUPPLY THROUGH MOTOR 8. POSITIVE GATE VOLTAGE 9. NO GATE VOLTAGE 10. NO GATE SIGNAL Figure 8. Transistor Control Figure 9. Average Motor Voltage 6

11 2200 SRM 411 Principles of Operation The accelerator potentiometer, at the speed control of the lift truck, regulates a voltage that changes as the operator sets the speed of operation. This voltage is an input to the controller and the pulse width modulator. As the voltage changes with the selected speed, a direct change in the ratio of FET ON TIME to FET OFF TIME also occurs. The voltage for maximum speed changes the ratio to pulses with the maximum ON TIME, to produce a maximum average motor voltage.seefigure9.thepulserate(15khz)stays thesameforallspeeds. Induction Current From Motor When a DC motor is controlled by a pulsed circuit, the magnetic field in the armature and field windings is continuously expanding and decreasing. The fields expand when voltage is applied (ON TIME) and decreases when the voltage is removed (OFF Table 1. TIME). The voltage causes an increasing current flow through the windings to make the expanding magnetic field. When the voltage is removed, the decreasing magnetic field causes current to flow in the same direction through the windings. See Table 1. This expansion and decrease of the magnetic field is lost energy for doing work unless the controller is designed to use this energy. A Flyback Diode (sometimes called a Freewheel Diode) is in the controller circuit for this purpose. The Flyback Diode permits the current, from the decreasing magnetic field, to flow through the field and armature again to do work. The torque of a series DC motor is directly proportional to the amount ofcurrent flowing through it. At slower speeds, the OFF times are longer. When the FETs are OFF, the decreasing magnetic field generates a voltage and current in the motor. Inductance Beginning conditions as the switch is closed: 1. Large current flow from battery through inductor. 2. Increasing magnetic field generates reverse voltage within inductor. 3. Reverse voltage decreases current through inductor. Current energy changed to energy in magnetic field. Constant conditions after switch is closed for a short time period: 1. Voltage and current flow is the same in all parts of the circuit. 2. Magnetic field is constant. Ending conditions as the switch is opened: 1. Decreasing magnetic field generates voltage within inductor. 2. Decreasing magnetic field generates current flow in original direction. 7

12 Principles of Operation 2200 SRM 411 This current is often called the flyback current. The Flyback Diode permits the current to flow through the field and armature again to do work. At slower speeds, the motor current is part battery current and part flyback current. There is less battery current used for the specific torque requirement. High current draw from the battery is to be avoided, if possible, because it is less efficient. At higher speeds, the OFF time is less, so that less induction current (flyback current) is generated. Most of the motor current must come from the battery at higher speeds. However, the torque and current requirements are also usually less. The typical induction current during equal ON and OFF timesofthefetsisshowninthegraphinfigure BATTERY 2. MOTOR ARMATURE 3. MOTOR FIELD 4. CONTROLLER 5. FETS (NOT ON) 6. FLYBACK DIODE Figure 10. Induction Motor Current Plugging The plugging circuit is an added feature of the controller that provides smooth electrical braking when the operator wants to change the truck s direction of travel. See Figure 11. The plugging feature also saves wear and tear on the drive tires and the drive unit gears. Plugging occurs when the truck is traveling in one direction but the operator has switched the directional control to the opposite direction. In this instance, the motor armature is rotating in one direction while the magnetic forces of the fields are trying to force the armature the other way. This reaction generates current that is allowed to flow through a loop formed by the plugging diode in the controller. This generated current helps to slow the truck s speed magnetically in the same manner that compression in a gas engine will help to control the speed of an automobile when it is coasting. When a lift truck is in the plugging mode, the pulse rate of the controller must be maintained at a slow rate. To accomplish this the logic section of the controller signals that the truck is in a plugging mode and controls the oscillating rate. The oscillating rate pulses slowly no matter what position the directional control is in on a controller with fixed plugging. Some controllers are furnished with throttle position plugging and the oscillating rate can vary. 8

13 2200 SRM 411 Principles of Operation Control Circuit The control circuit has operator inputs from the key and brake switches as well as the accelerator potentiometer. The circuit also has internal inputs from the power circuit for thermal protection, plugging sensing, low voltage protection and motor current (current limit). The control circuit uses the inputs to regulate the ON TIME pulses to the FETs for speed control, current limit and plugging strength. Static-Return-To-Off (SRO) Function The control circuit includes a function to prevent the operation of the lift truck if the starting sequence is not correct. The function uses the inputs to the control circuit to make sure the operator is ready to operate the controls. The starting sequence is as follows: 1. BATTERY 2. MOTOR ARMATURE 3. MOTOR FIELD 4. CONTROLLER 5. PLUG DIODE Figure 11. Plugging Current Circuit The plugging function of the controller is designed to allow the truck to travel 1 to 2 times the length of the lift truck after the truck is plugged before it reverses direction. During plugging, the oscillating rate is decreased from 15 khz to 1 khz. The controller regulates the pulse widths of the pulses to the motor field for the correct amount of plugging. The accelerator circuit is also set to a low speed so that normal acceleration in the opposite direction will occur. The plugging distance is adjustable. The plugging adjustment on the controller changes the amount of motor field current allowed. The plugging adjustment can be changed as needed for an application. See Adjustments. Plugging an electric lift truck is not a harmful practice, however, avoid plugging the drive motor when the drive wheel is jacked off the ground. 1. Turn the key switch to the ON position. The key switch supplies battery voltage to the brake switch. 2. The operator must close the brake switch. Battery voltage is now supplied to the control circuit. 3. Rotate the Direction/Speed control in the desired direction of travel to select travel direction and speed. If Step 3 is done before both Step 1 and Step 2 are complete, the lift truck will not move in either direction. The control circuit must get battery voltage through both the key and brake switches before it gets a speed signal from the accelerator potentiometer. If the starting sequence is not correct, the control circuit will not send a gate pulse to the FETs for traction motor current. The SRO function also prevents the lift truck from going to full speed operation because of a malfunction in the accelerator circuit. On the B/W40-60XL units, an open circuit in the accelerator circuit is normally sensed as a full speed signal by the control card. If this malfunction exists, the SRO function will prevent the start of traction pulses. If the malfunction occurs during normal operation, the control circuit senses an accelerator potentiometer input of more than 7000 ohms (open circuit) and stops the traction pulses. The circuit will return to normal operation after the malfunction is repaired. 9

14 Principles of Operation 2200 SRM 411 Thermal Protection Function There is a sensor to sense the heat within the controller housing. If the controller gets too hot or too cold for correct operation, the control circuit will reduce the ON TIME of the pulses to decrease the current to protect the controller. The lift truck will still operate at a slower speed to permit it to be moved to a location out of the work area. The controller can then return to a normal operating temperature. The controller is designed to operate with an internal temperature between 85 C(185F) and 25 C( 13 F). Controller performance will be reduced when the controller is in Thermal Protection. Low Voltage Protection Function This function protects the controller and the battery. The controller will not operate correctly if there is not a minimum voltage from the battery. The battery current drain increases as the battery voltage decreases. Too large a battery drain will damage the battery. If the battery voltage is low, the control circuit will decrease the ON TIME ofthepulsestodecrease the current drain. The battery can still operate the lift truck to move it for battery charging or replacement. The controller requires a minimum of 9 volts on the 12-volt controllers and a minimum of 16 volts on the 24-volt controllers for the system to function properly. Current Limit Protection Function The control circuit limits the traction motor current to a maximum value to protect the controller, motor and battery. The control circuit will decrease the ON TIME of the motor pulses to keep the motor current less than the maximum value. The maximum value is set by the manufacturer. Power Circuit The power circuit is controlled by the control circuit. SeeFigure12. Thecompletepowercircuitisinside the controller and has the following parts: Field Effect Transistors Flyback Diode Plug Diode Filter Capacitors The parts in the power circuit cannot be replaced by users. Cables connect the battery and traction motor to the power circuit at the controller power terminals B+, A2, M,andB. All of the traction motor current flows through the power circuit of the controller. 10

15 2200 SRM 411 Principles of Operation Figure 12. N30FR Transistor Controller Circuit Schematic 11

16 Sequence of Operation 2200 SRM 411 The sequence of operation describes a complete cycle of the transistor traction circuit. A sequence of the beginning conditions and the FET cycle is shown in Figure 13. NOTE: Gray lines on the circuit lines show positive voltage with respect to battery negative. Slash lines show negative voltage with respect to battery positive. The line codes do not always indicate full battery voltage. The gray tone is used only for the circuits being described. Some parts of the energized circuit are not shown with gray tones or slashes. The thick (bold) lines show the traction power circuit. The thin lines show the control circuits. NOTE: The following circuit schematics from the W40-60XL and B40-60XL lift trucks are used to describe the sequence of operation. Basic operation of the transistor controller for other lift truck models is similar. See the Diagrams sections for the complete schematics. NOTE: The N30FR, W40-60XL, and B40-60XL lift trucks have an additional LC contactor that is energized when the key switch closes. The basic circuit operation is the same as described. KEY SWITCH Key Switch closed by moving key to the ON position. On N30FR units, the LC contactor is energized. Battery power to brake switch, lift, lower, horn and to optional heater and battery meter. See Figure 14. BRAKE SWITCH Brakeswitchmustbeclosedbyloweringsteering handle (W/B40-60XL, W/B60-80XT, W20-40XTA, W20-40XTC, and W20-30XTR only); operator releasing brake handles (C60-80XT and T5XT); or operator stepping on brake switch (R30ES only) so that the FWD/REV switch, Traction Reverse switch (W/B40-60XL and W/B60-80XT only), Accelerator Potentiometer, and Control Circuit will have battery voltage when key switch is closed. See Figure 15. Sequence of Operation CONTROL CIRCUIT Battery positive to the Control Circuit, Hourmeter, Traction Reverse switch (W/B40-60XL and W/B60-80XT only), and Direction switch through the key and brake switches. Hourmeter begins to operate. Circuit checks that there is no speed signal from the accelerator potentiometer. If there is a speed signal as battery power is applied, the control circuit will prevent the gate signal from going to the FETs. See Figure 15. FWD/REV SWITCH CLOSED Forward contacts of FWD/REV switch close. Accelerator potentiometer speed signal to control circuit. Battery positive voltage available to Forward contactor. See Figure 16. FORWARD CONTACTOR ENERGIZED Normally open contacts of Forward contactor close. Normally closed contacts open. Battery positive voltageisappliedtofetsthroughtractionmotor.fets are still OFF, so there is no current flow and the traction motor does not operate. See Figure 17. GATE PULSE TO FETS Gate Driver of control circuit sends gate ON pulse to FETs gate. ON TIME (pulse width) set by accelerator potentiometer signal. See Figure 18. FETS ON FOR TIME OF GATE PULSE FETs conduct to provide power pulse to the traction motor. Traction motor starts to operate. Pulse ON TIME isthesameasgateon TIME. SeeFigure18. GATE PULSE REMOVED FETs stop conducting when gate pulse is removed. Power pulse is removed from traction motor. Pulse OFF TIME is set by the time remaining for one cycle at 15 khz. See Figure

17 2200 SRM 411 Sequence of Operation Figure 13. Sequence of Operation 13

18 Sequence of Operation 2200 SRM 411 NOTE: W/B40-60XL SHOWN. OTHERS SIMILAR. Figure 14. Sequence of Operation - Key Switch Closed 14

19 2200 SRM 411 Sequence of Operation NOTE: W/B40-60XL SHOWN. OTHERS SIMILAR. Figure 15. Sequence of Operation - Power to Control Circuit 15

20 Sequence of Operation 2200 SRM 411 NOTE: W/B40-60XL SHOWN. OTHERS SIMILAR. Figure 16. Sequence of Operation - Direction/Speed Control Set for Slow Forward Speed 16

21 2200 SRM 411 Sequence of Operation NOTE: W/B40-60XL SHOWN. OTHERS SIMILAR. Figure 17. Sequence of Operation - Forward Contactor Energized 17

22 Sequence of Operation 2200 SRM 411 NOTE: W/B40-60XL SHOWN. OTHERS SIMILAR. Figure 18. Sequence of Operation - Gate Pulse to FETs, FETs ON 18

23 2200 SRM 411 Sequence of Operation NOTE: W/B40-60XL SHOWN. OTHERS SIMILAR. Figure 19. Sequence of Operation - FETs OFF 19

24 Sequence of Operation 2200 SRM 411 INDUCTION CURRENT FLOWS THROUGH MOTOR AND FLYBACK DIODE Induction current, generated by motor, flows through the flyback (freewheel) diode and returns through the motor. This current is used instead of battery current to keep the motor operating. See Figure 20. PLUGGING Plugging is a method of stopping an electric lift truck by changing the direction of current flow in the motor field. Figure 21. To actuate the plugging circuit, the operator must change the Direction/Speed control for travel in the opposite direction of present travel. NOTE: W/B40-60XL SHOWN. OTHERS SIMILAR. Figure 20. Sequence of Operation - Induction Current 20

25 2200 SRM 411 Sequence of Operation NOTE: W/B40-60XL SHOWN. OTHERS SIMILAR. Figure 21. Sequence of Operation - Plugging The controller prevents motor current flow during the time the FWD/REV contactors change to the reverse direction. The controller senses when the FWD/REV switch goes through neutral and momentarily interrupts the battery positive input from the key and brake switches. This action momentarily turns the FETs OFF when the high current flow can cause an arc and burn the contactor contacts. The controller senses plugging action by the voltage across the plug diode. The frequency of the oscillator is reduced from 15 khz to 1 khz to limit torque. Current limit is also reduced to prevent the plugging current from becoming too great. This current limit can be changed by the external plugging adjustment. The controller regulates the pulse widths of the pulses to the motor field for the correct amount of plugging. The controller accelerator circuit is also set to a low speed so that normal acceleration in the opposite direction will occur after the lift truck comes to a stop. The motion of the lift truck drives the traction motorarmaturetomakethemotoroperateasagenerator. This additional generator current (armature current) adds to the current flow through the field to reverse the motor at an even faster rate. Unless 21

26 Checks 2200 SRM 411 the control circuit provides a way to slow this change of direction, the lift truck will stop very quickly. The plug diode in the control circuit prevents the lift truck from stopping too quickly. While the motor is acting as a generator, the plug diode prevents this generator current from adding to the field current. The control circuit lets all of the plugging current flow from the armature through the plug diode, then flow with the battery current through the armature again. This reduces the effect of the induction current. WARNING Do not make repairs or adjustments unless you have both authorization and training. Repairs and adjustments that are not correct can create a dangerous operating condition. Do not operate a lift truck that needs repairs. Report the need for repairs to your supervisor immediately. If repair is necessary, put a DO NOT OPERATE tag on the control handle. Remove thekeyfromthekeyswitch. Checks B terminals (seefigure23)ofthetransistor controller. Some checks require the battery connected. Do not connect the battery until the procedure tells you to connect the battery. Make sure the drive wheel is raised to prevent truck movement and possible injury. Raise the drive wheel as described in the Operating Manual or the Periodic Maintenance section of the Service Manual. There are several checks that can be made that check for correct operation of the system. There are only two external adjustments on early units and three adjustments on later units. There are no internal adjustments for the transistor controller. NOTE: The checks require a volt-ohmmeter with a meter movement. Most digital meters will not operate correctly for some of the checks. Specific checks require additional equipment. CHECKING CONTACTOR COIL WARNING Disconnect the battery and separate the connector before opening the hood or inspecting or repairing the electrical system. If a tool causes a short circuit, the high current flow from the battery can cause an injury or parts damage. The capacitor in the transistor controller can hold an electrical charge after the battery is disconnected. To prevent electrical shock and injury, discharge the capacitor before inspecting or repairing components under the hood. Wear safety glasses. To discharge the capacitor, first disconnect the battery. Then connect an insulated jumper wire between the B+ and Check the Forward or Reverse contactor coil with an ohmmeter. A suppressor diode with a resistor in series is partofthecoil.thediodewillcausetheohmmeter to indicate a difference in resistance in one direction. Reverse the probes of the ohmmeter to the opposite terminals and measure the resistance. Use the highest resistance indication. Replace the coil if the resistance readings are a short circuit in both directions or if there is an open circuit in both directions. Make sure the coil wires are connected again to the correct terminals. CHECKING TRANSISTOR CONTROLLER These checks are in two sections: checks with the controller installed in the lift truck and checks of the controller out of the lift truck (bench checks). The controller is protected against operation with a low battery. Controller output is slowly decreased as battery voltage decreases. The battery can be low if an operator notices slower operation or less power. This operation is not a defect of the transistor controller. Make sure all checks are done with a fully charged battery. NOTE: The following checks must be done in the order they are listed because some steps depend on conditions set in previous steps. 22

27 2200 SRM 411 Checks Checks With Controller Installed 1. Raise the drive/steer wheel as described in the Operating Manual or the Periodic Maintenance section of the Service Manual. 2. Make sure the battery is fully charged. 3. Make a physical check to be sure that battery negative is connected to the B terminal of the controller. Connect the negative meter lead to the B terminal. 4. Check for battery positive voltage at the B+ terminal of the controller (see Figure 23) and the cable P2 terminal of the Reverse contactor. If there is no battery positive voltage, check the cables between battery positive and the two terminals. Ifthecablesarenotdamaged,thecontrollercan be damaged. 5. Tag all wires and cables before they are removed. Make sure the key switch is in the OFF position and remove the wires from terminals 1 and 2 of the controller. See Figure 22 and Figure 23 for the correct unit. If a resistor is used between terminals 1 and 2, do not disconnect the resistor. Check for an open circuit (at least 1 megohm) between the wires with the Direction/Speed control in the NEUTRAL position. If there is no open circuit, check to see that the accelerator potentiometer is in the centered position. Check for maximum resistance by moving the control to the full speed position(s). See the following chart. Check for at least one megohm resistance between each wire and the lift truck frame. If any of the resistance readings are wrong, check the wiring to the accelerator potentiometer and check the adjustment of the FWD/REV switch. Connect wires to terminal 1 and terminal 2. See the sections Diagrams 8000 SRM 457, Diagrams 8000 SRM 475, Diagrams 8000 SRM 495, or Diagrams 8000 SRM 653 for the walkie high lift motorized hand trucks. Pot P/N Rotation unidirectional Resistance Neutral 4.5K to 5.5K Resistance Full Speed 50 to bi-directional Infinity bi-directional 0to bi-directional 3.5K 0 All values ±10% Figure 22. New Controller 4.5K to 5K 23

28 Checks 2200 SRM 411 NOTE: SOME CONNECTORS HAVE DIFFERENT FUNCTIONS DEPENDING ON MODEL OF LIFT TRUCK AND MODEL OF CONTROLLER USED. 1. M POWER TERMINAL 2. TERMINAL 2 3. TERMINAL 1 4. B POWER TERMINAL 5. B+ POWER TERMINAL 6. KEY SWITCH INPUT 7. F/R CONTACTOR OUTPUT 8. STATIC-RETURN-TO-OFF, 1A OR NOT USED ON W40XT, W45XT, W/B/C60-80XT, AND T5XT 9. BRAKE OR TRACTION REVERSE (W/B40-60XL, W40XT, W45XT, AND W/B60-80XT ONLY) 10. FORWARD INPUT 11. REVERSE INPUT 12. A2 POWER TERMINAL Figure 23. Controller Wire (Control) and Cable (Power) Terminals 6. Connect the voltmeter positive lead to the controller B+ terminal. Connect the voltmeter negative lead to the controller M terminal. Move the key to the ON position, lower the control handle (W/B40-60XL, W/B60-80, W40XT, W45XT, W20-40XTA, W20-40XTC, W20-30XTR), or step on the brake switch (R30ES, N30FR). Release the brake levers (C60-80XT and T5XT units). Check for zero or near zero volts. Move the Direction/Speed control for full speed travel. Check for full battery voltage. 7. If there is not full battery voltage, the controller is defective. If there is battery voltage and the motor does not operate, disconnect the battery connector and discharge the internal capacitor. The correct procedure to discharge the capacitor is described in the WARNING at the beginning of this section. 8. Disconnect the cable from the controller A2 terminal. Use the ohmmeter to check for a diode between the A2 and B+ terminals. There must be a high resistance in one direction and a low resistance with the meter leads reversed. If there is a low or high resistance in both directions, the diode is damaged. If the readings are correct and the motor does not operate, there is a short circuit in the motor circuit. Check for a short circuit at the motor cables or direction contactors. If there are no short circuits, the motor has a short circuit. Replace any defective item(s). 9. Connect all wires or cables that had been disconnected. 24

29 2200 SRM 411 Checks Bench Checks To test the controller on the bench, you will need the following equipment (see Figure 24): A power supply with a voltage equal to the lift truck voltage. The power supply can be any of the following: the lift truck battery, automotive batteries connected in series or an AC power supply with a regulatedd.c.outputof12to48volts. Onlylow power tests will be done, so a 10-amp fuse is wired in series with the power supply to protect the operator and controller from accidental short circuits. Do NOT use a battery charger as a power supply since the no load voltage can be higher than the voltage of the controller. A speed control, a 5K ohm potentiometer wired as a2-terminalrheostatwillworkfine. A contactor (similar to the pump motor contactor) with a 5-watt, 250-ohm resistor across the contacts. A toggle switch and key switch connected as shown arealsoneeded. A test load of incandescent lamps with a voltage equal to the lift truck voltage. 12-volt lamps wired in series work fine. A multimeter or digital voltmeter. 1. Shake the transistor controller to see if any parts arelooseinside. Iftherearelooseparts,replace the controller. 2. Connect the controller as shown in Figure 24. Connect the voltmeter to the B+ and B terminals of the controller. 1. POWER SUPPLY AMP FUSE 3. TOGGLE SWITCH 4. KEY SWITCH 5. CONTACTOR 6. RESISTOR 7. TRANSISTOR CONTROLLER 8. TEST LOAD 9. SPEED CONTROL Figure 24. Bench Checks 25

30 Checks 2200 SRM Make sure the key switch is OFF. Turn the power supply and toggle switch ON. Look at the voltmeter. The voltmeter indication must slowly increase to the truck voltage. If the voltage does not increase to the truck voltage, replace the controller. 4. The lamps must not illuminate now. If they illuminate, replace the controller. 5. Move the key switch to the ON position. 6. Move the speed control and look at the lamp brightness. The lamps must slowly increase in brightness as the speed increases. 7. Test the controller s SRO functions: a. Turn the key switch to the OFF position. b. Move the speed control to the full speed position. c. Turn the key switch to the ON position and check that the lamps do NOT illuminate until the speed control is moved to OFF and returned to ON. 8. Check the controllers fault function by removing a wire from terminal 2 or 3 on the controller. The lamps must NOT illuminate. 9. Disconnect all wires and cables from the controller and use the ohmmeter or diode checker to check the plug diode. Connect the meter between the A2 and B+ terminals. Reverse the meter leads and check the reading. There must be a high resistance in one direction and a low resistance with the meter leads reversed. If there is a low or high resistance in both directions, the diode is damaged. Replace the controller. 10. Check the flyback (freewheel) diode. Connect the meter between the M and B+ terminals. Reverse the meter leads and check the reading. There must be a high resistance in one direction and a low resistance with the meter leads reversed. If there is a low or high resistance in both directions, the diode is damaged. Replace the controller. Accelerator Potentiometer Checks and Adjustments The following procedures are for checking and adjusting the accelerator potentiometer and control switches for the W/B40-60XL units ONLY. different series of lift trucks have their own checks and adjustments. See the sections for the following models: N30FR, N40-50FR, N50FA - Electrical Adjustments 2200 SRM 381 and Diagrams 8000 SRM 495. R30ES - Electrical System 2200 SRM 420 and Diagrams 8000 SRM 475. W40XT, W45XT, W/B/C60-80XT, T5XT - Electrical System 2200 SRM 279 and Diagrams 8000 SRM 457. W20-40XTA, W20-40XTC, W20-30XTR - Electrical System 2200 SRM 279 and Diagrams 8000 SRM 653. NOTE: The direction switch must be correctly adjusted before the accelerator potentiometer can be checked. The accelerator potentiometer must be adjusted after each installation. 1. Make sure the battery is disconnected and the capacitor in the controller is discharged. The correct procedure to discharge the capacitor is described in the WARNING at the beginning of this section. 2. Adjust the accelerator potentiometer when it is installed with the pulley belt in place and both wires disconnected. 3. Connect an ohmmeter between wires 15 and 16 on the accelerator potentiometer. 4. Rotate the direction and speed control. The ohmmeter will indicate changes of resistance. Loosen the two setscrews in the pulley block. Adjust the potentiometer in the pulley block so that when the control is in the neutral position, the ohmmeter shows maximum resistance. The maximum resistance of the potentiometer will be approximately 4750 ±0%. 5. Tighten the two setscrews on the pulley block. Do not let the pulley or shaft move as the setscrews are tightened. 6. Rotate the direction and speed control to the forward and reverse directions. Check that the resistance of the potentiometer is less than 200 ohms at the maximum speed positions. 7. Connect the wires 14, 15, and 16 from the accelerator potentiometer to the correct wires on the lift truck and the traction reverse switch. Install the cover plate and connect the battery. 26

31 2200 SRM 411 Adjustments WARNING Disconnect the battery and separate the connector before opening the hood or inspecting or repairing the electrical system. If a tool causes a short circuit, the high current flow from the battery can cause a personal injury or property damage. The capacitor in the transistor controller can hold an electrical charge after the battery is disconnected. To prevent electrical shock and personal injury, discharge the capacitor before inspecting or repairing components under the hood. Wear safety glasses. To discharge the capacitor, first disconnect the battery. Then connect an insulated jumper wire between the B+ and B terminals ( Figure 23) of the transistor controller. Some checks require the battery connected. Do not connect the battery until the procedure tells you to connect the battery. Make sure the drive wheel is raised to prevent truck movement and possible injury. Raise the drive wheel as described in the Operating Manual or the Periodic Maintenance section of the Service Manual. Adjustments Limit.SeeFigure25.Theoldercontrollershavetwo adjustments, Braking and Controlled Acceleration. The plugging adjustment adjusts how far the lift truck travels before reversing direction. The Direction/Speed control can be moved to the maximum speed position from stop or a slow travel speed. The controlled acceleration adjustment allows adjustment of the maximum rate of acceleration. The Current Limit adjustment controls the motor current to a preset maximum. WARNING Do not make repairs or adjustments unless you have both authorization and training. Repairs and adjustments that are not correct can create a dangerous operating condition. Do not operate a lift truck that needs repairs. Report the need for repairs to your supervisor immediately. If repair is necessary, put a DO NOT OPERATE tag on the control handle. Remove thekeyfromthekeyswitch. NOTE: The new 1243 controller as no adjustment it is preset and has electronic boxes connected by the Can bus data link system. NOTE: The SEM motor controller operates on the principle of controlling the motor field circuit and the motor armature circuit independently. The SEM controller includes a full range of built-in safety features and diagnostic and setup capability for safe reliable operation. The older controller has three adjustments: Braking (plugging), Controlled Acceleration, and Current A. MIDPOINT ADJUSTMENT 12 O CLOCK POSITION B. MINIMUM ADJUSTMENT C. MAXIMUM ADJUSTMENT D. ENLARGED VIEW OF ADJUSTING SCREWS (2, 3, AND 4) 1. TRANSISTOR CONTROLLER 2. BRAKING (PLUGGING) ADJUSTMENT SCREW (CW = HARDER BRAKING) 3. CURRENT LIMIT ADJUSTMENT SCREW (CW = HIGHER CURRENT) (NOT USED ON W/B40-60XL CONTROLLERS) 4. CONTROLLED ACCELERATION ADJUSTMENT SCREW (CW = FASTER ACCELERATION) Figure 25. Controller Adjustment Locations 27

32 Repairs 2200 SRM 411 Alladjustmentsaremadewiththekeyswitchoff and the battery disconnected. Discharge the capacitor. Remove the nylon seal washer and the 3 mm (0.12 in.) socket head screws to access the adjustment screws. Make the adjustments using a small insulated screwdriver. Replace the socket head screws and nylon seal washers after all adjustments are made. Tighten the setscrews to 0.9 N m (8 lbf in). PLUGGING ADJUSTMENT Turning the braking (plugging) adjustment clockwise will increase the plugging effect and stop the lift truck in a shorter distance. Turning the adjustment counterclockwise will decrease the plugging effect. The traction motor brushes have a faster wear rate when the control is set for the shortest stopping distance (maximum plugging). More heat is also generated in the traction motor at this maximum setting. This adjustment should be set in the one o clock position. ACCELERATION ADJUSTMENT Turning the controlled acceleration adjustment clockwise will increase the acceleration rate. Turning the adjustment counterclockwise will give a slower rate of acceleration. The traction motor brushes have a faster wear rate when the control is set for an increased acceleration rate. More heat is also generated at this maximum setting. This setting should be set in the twelve o clock position. CURRENT LIMIT ADJUSTMENT Turning the current limit adjustment clockwise will increase the current limit. This setting is factory set at the maximum 400 amps. The truck will also run at a higher than normal speed especially when it has no load. Lowering this adjustment can cause the truck to have limited starting torque and can cause the truck not to run at top speed when fully loaded. This setting should be set at the maximum adjustment position. Repairs CONTACTORS WARNING Disconnect the battery and separate the connector before opening the hood or inspecting or repairing the electrical system. If a tool causes a short circuit, the high current flow from the battery can cause a personal injury or property damage. The capacitor in the transistor controller can hold an electrical charge after the battery is disconnected. To prevent electrical shock and personal injury, discharge the capacitor before inspecting or repairing components under the hood. Wear safety glasses. To discharge the capacitor, first disconnect the battery. Then connect an insulated jumper wire between the B+ and B terminals (Figure 23) of the transistor controller. Some checks require the battery connected. Do not connect the battery until the procedure tells you to connect the battery. Make sure the drive wheel is raised to prevent truck movement and possible injury. Raise the drive wheel as described in the Operating Manual or the Periodic Maintenance section of the Service Manual. The FORWARD and REVERSE contactor assembly controls the direction of current flow through the traction motor. See Figure 26. The contactor is a heavy-duty switch that opens and closes the power circuit. The traction circuit has a FORWARD and REVERSE contactor assembly. Each contactor assembly has the following parts: two sets of normally open (NO) contacts, two sets of normally closed (NC) contacts and a coil. The coil is an electromagnet that moves the NO contacts to the closed position against spring pressure. The coil is in the control circuit. The contactor tips are in the traction circuit. A suppressor is part of each coil. When a contactor coil is energized, the normally open (NO) contacts close and the normally closed (NC) contacts open. Current flows through the traction motor fieldinonedirectionwhentheforwardcontactor is energized and in the other direction when the RE- VERSE contactor is energized. This action gives direction control to the traction motor. The contacts normally have a long service life because the current flow through the contacts is stopped before the contactsopen. TheFETsareOFF before the contactor coil is de-energized. 28