COLDWATER LAKE FACILITIES DUPLEX PUMP STATION TROUBLESHOOTING GUIDE REFERENCE: Operation Instructions Ladder Schematic Diagrams SCOPE The following troubleshooting guide has been specifically prepared for this system. It primarily relates to electrical failure. When problems develop a good troubleshooting technique is most important. The following guide will not cover all circumstances. Many mechanical functions are beyond the scope of this guide. Mechanical functions should be dealt with by people knowledgeable of the equipment. A pump overload can be caused by mechanical problems relating to the pump and motor such as bearings, foreign material in pump binding seals, misalignment, etc. 1.0 GENERAL 1.1 ORGANIZATION The troubleshooting guide format is arranged in three general areas: 1- A discussion of common problems 2- A discussion of problem isolation techniques 3- A list of symptoms with associated possible causes In most cases identification of the cause will result in obvious corrective action. 1.2 SUGGESTIONS Any changes that may be associated with a problem can be very helpful. Any unusual noise, smell vibration, etc., may give a good clue as to the ultimate cause. A routine inspection of the panel to look for any changes should be conducted. Look for: noise, humming, excessive dust, discoloration, smoke, burning smell, disconnected wires, vibration, chattering, heat, burning, extra loose screws, other loose parts, etc. A most useful test on an energized system is to check for the presence of power directly on a suspected component. 1
On a de-energized system test the suspected components with an ohmmeter to determine that the resistance is in expected range. 1.3 ADJUSTMENT Do not touch or adjust anything without being sure you know what you are doing. All adjustable components have either been factory set or set upon first start-up. A change that requires field readjustment is unusual. If a change is made care should be exercised that the original settings are noted. Original settings can thereby be re-established if necessary. 1.4 SAFETY The electrical energy levels present in the circuits of this system during normal operation are potentially very dangerous, do not take any chances. When working on the equipment assume that all electrical parts are energized. Even though all direct connections normally supplying power to a panel are broken some parts may still be "HOT". All work involving entry into an electrical panel should only be accomplished by a knowledgeable technician. Check for foreign voltages on outgoing terminals. 2.0 COMMON PROBLEMS 2.1 MOTOR OVERLOAD Cause may be electrical or mechanical. Possible mechanical problems could include: contamination or failure of bearings, fouling of motor shaft or impeller, broken or plugged pipe, etc. Possible electrical problems could include: shorted turns in motor windings. unusually high voltage, unusually low voltage, bad electrical connection, etc. If the motor overload/breaker trip light has come on try resetting the motor starter overload and try again to run the motor. A second overload trip should be investigated before resetting. If resetting the motor starter overload does not allow the motor to start probable cause is the motor circuit protector trip. See the following paragraph. 2.2 MOTOR CIRCUIT PROTECTOR (MCP) TRIP Most MCP trips are caused by winding insulation failure in the motor. If possible, inspect the motor before resetting and attempting to run again. Persistent "nuisance" tripping indicates a problem in the system, too low a setting on the MCP trip point, or insufficiently large heater in the starter. Refer to the catalog section of this manual to understand the method of setting the MCP trip point and to compare motor amps to heater size. 2
2.3 INPUT SWITCH FAILURE The action of the input switches may be simulated with test switches. If operation is not normal (see operation instructions) check input switches with the test switches as follows: 1- A switch that should be closed, but is not, can be tested by moving the test switch to "C". If the desired function takes place, this indicates an input switch has failed. If not, a problem in the panel may be indicated. 2- A switch that should be opened by is not, can be tested by moving the test switch to "O". If the desired function takes place, this indicates an input switch failure or water in the wiring. If not, a problem in the panel may be indicated, If water in the wiring is suspected, see paragraph 2.4 following. 3- Normal function test. Sequential operation of the test switches can be used to simulate complete system automatic cycling. 4- Be sure to return test switches to the proper position after testing, Normally, the switches should be in "A". There are cases where either the "O" or "C" position may be desired for abnormal conditions. 2.4 DESENSITIZING D.C. RELAYS FOR LEAKAGE A relay may have to be desensitized due to leakage from a leaky cable. If water gets into wiring of a remote switch, leakage resistance may occur causing the switch to always appear closed to the controls. A sensitive D.C. relay, such as the Midtex 611 series used on this panel, can be adjusted to still work by adding a resistor in parallel with the coil of the relay. A resistor is needed if the relay will not turn off when the float switches are open. Voltage measurements should be made with a digital voltmeter with 10 MEGOHM input impedance. 1- Make sure contacts in the relay circuit are open. 2- Measure voltage across pins 8 to B on the relay socket. If the voltage is greater than 1.0 volts a resistor is required to desensitize the relay. Example: Voltage measured is 6 volts. Graph says a 6K ohm resistor is required. Use a resistor 1/2 that of size indicated, 3K ohm. Do not use below 2K ohm if graph indicated less than 4K ohm is required. 3- Install the resistor between pins 8 and B on relay socket. 3
If the contacts are open, re measure voltage across pins 8 and B. Voltage should be less than 1.0 volts. If not, use the next smaller size resistor until voltage is less than 1.0 volts when float switches are on open circuit. For probes, the procedure is the same as for float switches except that when probes are in the water, the voltage across pins 8 and B must be a least 3.0 volts to operate reliably. Voltage should be less than 1 volt when probes are out of the water. 3.0 PROBLEM ISOLATION This system has been provided with specific alarm indicator lights to indicate expected common problems. The labels on the alarm lights are generally self-explanatory and should lead you directly to easy correction of the problem. For example, if the overload indicator light goes on, a correction can probably be accomplished by resetting the motor overload or the motor circuit protector. The detailed isolation of a problem can also be associated with the general area of power supply within the panel. Control power is available at 120 volts AC, 24 volts AC, and 24 volts DC. There is a higher voltage AC power available to run the motors. Note that although a problem may be isolated to one of the areas of power, some components may cause problems that are involved with more than one section. For example, relay R1 is in the DC control voltage circuit, but has operating contacts in the AC circuitry. There are four types of plug-in relays used in this system: 24 volt DC relays with 11 pin square sockets, 24 volt AC relays with 11 pin round sockets, a 24 volt AC alternating relay with 8 pin round socket, and a adjustable voltage monitoring relay in the 115 volt range with an 8 pin round socket. Relays that are alike may be swapped in order to help troubleshoot. A malfunction that appears associated with a given function can be tested by swapping it's relay with another identical relay. If the malfunction follows the relay the apparent cause is a problem with the relay. For help in determining what relays to try swapping refer to the ladder schematic diagram. Also refer to the schematic diagram to understand the function of the test switches. There is a test switch at each input switch so that the operation can be completely checked as though all the input switches were operating. 4
4.0 SYMPTOMS AND POSSIBLE CAUSES SYMPTOM Continuous signal that an input input switch is closed. Continuous signal that an input switch is open. Pumps will not run in AUTO. All lights out. General alarm lights ON, Horn switch ON, horn not sounding. POSSIBLE CAUSE Test switch in "O". Water in wiring. Faulty input switch. Test switch in "C". Broken wire. Faulty input switch. Open float circuit. R1, R6, R7, RA, OL1, OL2 Tripped circuit breaker. MCP's. Power input. Power input. Tripped circuit breakers. GFI. DC power supply malfunction. CB3. PB1A R5. 5