Motor Protection With The MonitorPro

Transcription

1 Motor Protection With The MonitorPro This application note can show you the easy way to protect your motors and your pump stations. The MultiTrode MonitorPro can protect your motors from a wide range of common faults, and even perform routine testing to predict emerging faults and has the following features as standard: Inbuilt Insulation Resistance Tester means no wiring removal, and no site visit necessary Over-current detection can detect damaged motors, blocked pumps or seized bearings Under-current detection can detect damaged impellors or burst pipes. Electronic thermal protection ensures against degradation of windings from over-temperature far more reliably than simple thermistor or bi-metallic overloads. Supply voltage monitoring can protect against surges, brownouts, or phase dropouts. 1 Hardware To protect your motors, your site requires the following minimum hardware installed in addition to your MultiTrode Pump Controller and MultiTrode MonitorPro: One Current Transformer (CT050 or CT100) per phase per motor CT050 has a 5A output for a 50A input CT100 has a 5A output for a 100A input One Current Shunt Adapter (SR1 or SR5) per 3-phase motor o o SR1 has a 50mV output for a 1A input SR5 has a 50mV output for a 5A input 2 Wiring See the wiring diagram on the next page for connection details. 2.1 Supply Voltage Monitoring For supply voltage monitoring, you must connect 3 Phase AC supply to L1, L2, L3 inputs. The voltage measurements are performed with respect to the AC Supply Earth, so the Mains Power Terminal E must be securely earthed to the same earth as the motors. 2.2 Motor Protection For Motor Protection, you must connect Current Transformers and Current Shunt Adapters into terminals AR/AW/AB to CR/CW/CB and T1 to T9..doc 6 July 2005 Page 1 of 6

2 2.3 Motor Insulation Resistance Testing For the motor insulation resistance testing you must connect one phase of each motor to the insulation to resistance tester inputs MEGGER, MA, MB and MC. The insulation resistance test is performed with respect to the AC Supply Earth, so the Mains Power Terminal E must be securely earthed to the same earth as the motors. Figure 1 The back panel of the MonitorPro showing terminal locations. The wiring connections for motor protection and supply voltage monitoring are show in the wiring diagram at right. Note: Detail is not relevant to the supply monitoring and motor protection wiring is not shown. See the MonitorPro manual for a full wiring diagram..doc 6 July 2005 Page 2 of 6

3 3 Precautions Before attempting to program the MonitorPro, ensure you have all of the nameplate details from your motors. The MonitorPro has a built-in 500VDC Insulation Resistance Tester. If you are using an inverter or a soft starter, check with your supplier about compatibility before using the Insulation Resistance Tester function on the MonitorPro. The MonitorPro will emit 500VDC for a short period, and this is normally immediately after the motor is stopped. This test may cause damage to the inverter or soft starter, or false readings could be obtained due to leakage through the inverter or soft starter. This danger is especially likely if the inverter has a ramp-down time or a DC brake programmed, as the MonitorPro would be performing the Insulation resistance test while the inverter is still driving the motor. It should also be noted that only one wire on each motor is directly connected to the MonitorPro s Insulation Resistance Tester. The MonitorPro is relying on the internal connections of the coils to test the other coils. If a Star / Delta switcher is being used, it should be configured so that the 3 coils on the motor are connected in either format (i.e. not isolated from each other) when the test will be performed. In software versions and above, there is a one-minute delay between when the motors are stopped by the MonitorPro and the insulation resistance test is performed. This is to allow inverters to slow the motor down or perform DC braking, so that the insulation resistance test is not performed while the inverter is powering the motor. The software version of your equipment is recorded on the back of the unit, where the wiring terminals are located, or is visible on the display when the unit is reset. A reset can be performed from the front panel by pressing the Left, Right and Help buttons simultaneously. 4 Programming To set the MonitorPro up for motor protection, proceed as follows from the front panel of the MonitorPro: 4.1 Enter the menu structure of the MonitorPro, and then select the STATION SETUP menu. Motor Insuln Fault :->Disabled Level (MOhm) :01.0 Test Frequency :All pumps stopped 4.2 To set up the Automatic Insulation Resistance Testing, Enter the Motor Protection menu, then the General menu. If you don t wish to configure the Insulation Resistance Testing, ensure the screen shows the Motor Insuln Fault as Disabled, then jump ahead to step To turn the Insulation testing function on, set the Motor Insuln Fault to Enabled. 4.4 At the Level line, enter the insulation resistance level below which the MonitorPro should return a failed test. This value is entered in Mega-ohms (MΩ). If a motor fails a test, it will be locked out, and will not be available for use. Although the legal limit in Australia is 1MΩ, we recommend a much higher value, such as 5MΩ, to predict faults earlier, before they become a problem. 4.5 The test frequency will determine how often the Automatic test is performed. This can be daily, weekly, or when all the pumps are stopped. If a daily (or weekly) frequency is selected, the test will be performed upon the next motor stop 24 hours (or 7 days) after this menu is exited. If All Pumps Stopped is selected, the insulation resistance test will be performed every time the motors stop (or 1 minute after, for software versions and above). This is the optimal time to perform the test as the motors are at their operating temperature..doc 6 July 2005 Page 3 of 6

4 4.6 Pressing down will select the next screen. The Reset Mode will determine how the motor will be brought back into service in the event of a failed insulation resistance test. If an Auto setting is selected, after the nominated time the motor will be retested and if it passes the test, will be re-enabled. A Manual reset mode means that the motor will be locked out until the fault is manually reset by pressing the reset button on the front of the Pump Controller. As a failed insulation resistance test is a serious problem, we recommend that the Reset Mode be set to Manual. 4.7 Pressing Enter while the arrow is pointing at Test Now will initiate a insulation resistance test on all connected motors. Note that this test will be performed regardless of the status of the motors according to the Pump Controller. If a motor is running, or the inverter or soft starter is injecting any sort of power or signal into the motor (e.g. slowing down or DC brake) when the test is performed, incorrect readings may be obtained. When the test is complete, the MonitorPro will return to the main display. The results of the insulation resistance test can be seen by pressing the down arrow once. Reset Mode :->Auto - 1 min Immediate Test :Test Now 4.8 Re-enter the menu system and enter the Motor Protection menu, then the Pump 1 Menu. 4.9 The Motor Protection menu sets up the parameters needed to adequately protect your motor. The screens are shown sequentially below, with a brief description of the use of the specific parameter, as well as the reference to the MonitorPro manual section that contains more information on each parameter. CTPrimaryFLC(Amps) :->050.0 Locked Rotor Fault :Enabled Level (Amps) : CTPrimaryFLC(Amps) see section of the manual. The CTPrimaryFLC is the Full Load Current of the Primary coil of the Current Transformer. If the motor cable is only passed through the current transformer (normal situation), the value should be entered as read off the Current Transformers used. If the current transformer is being used to measure a much lower current than for what it is rated, then the motor cable should be passed through the Current Transformer a number of times, and the CTPrimaryFLC parameter would be entered as: Specified Current Transformer Primary Rating CTPrimaryFLC = Number of turns of motor cable through Current Transformer 4.11 Locked Rotor Fault see section of the manual. Enabling this option will set off an alarm if the measured motor current exceeds the Level shown on the next line for longer than the Operate Delay shown on screen Level (Amps) see section of the manual. This level is the level above which the Locked Rotor Fault will trip an alarm. Operate Delay(sec):->010 Reset Mode :Auto 1min Thermal Protn :Disabled.doc 6 July 2005 Page 4 of 6

5 4.13 Operation Delay see section of the manual. This is the time that the measured motor current must be above the Locked Rotor Current Level before the alarm is tripped Reset Mode see section of the manual. The Reset Mode determines how the locked rotor fault should be reset after it has been tripped. If the Reset Mode is set to Auto x min, then after the time period shown, the MonitorPro will attempt to restart the motor. If the fault still exists, the motor will not be restarted. If the Reset Mode is set to Auto (with no time period shown), the MonitorPro will reset the unit automatically as soon as the fault is cleared. As the motor is shut down when the fault occurs, the fault will immediately clear, and so the motor will immediately be re-enabled. For this reason, we recommend to not use the Auto setting Thermal Protn Section of the manual. Enabling this option allows the MonitorPro to perform Thermal Protection of the motor, and will shut the motor down if the calculated thermal current exceeds the limit set on the next screen. P 1 3/7 Motor FLC (Amps) :-> xFLC Trip Time(s):010 Reset Mode :Auto 5min 4.16 Motor FLC (Amps) see section of the manual. This is the Full Load Current of the motor, as specified by the motor manufacturer. This should be entered as read off the motor nameplate XFLC Trip Time(s) see section of the manual. This is the time that the measured current has to be above the FLC limit. This should be entered as read off the motor manufacturers data sheet. If the manufacturers data sheet cannot be obtained the recommended value of 10 seconds should be used. See section of the MonitorPro manual for calculating other values according to manufacturers data Reset Mode see section of the manual. The Reset Mode determines how the 6xFLC fault should be reset after it has been tripped, as per the reset mode for the locked rotor fault in section OTECTION: PUMP 1 4/7 UnderCurrent Flt :->Enabled Level (Amps) : Operate Delay(sec) : UnderCurrent Flt see section of the manual. Enabling this fault will cause a fault trip if the measured motor current is below the level specified on the next line Level (Amps) see section of the manual. This is the level below which the motor is determined to have failed on an undercurrent fault Operate Delay(sec) see section of the manual.. This is the time that the measured motor current must be below the under-current fault level before a fault is tripped Reset Mode see section of the manual. The Reset Mode determines how the under-current fault should be reset after it has been tripped, as per the reset mode for the locked rotor fault in section Phase Failure Fault Section of the manual.. Enabling this fault will cause a fault trip if the three measured voltages on the three-phase supply are different by the level shown on the next line. Reset Mode :->Auto 5min Phase Failure Fault :Disabled Level (%) :25.doc 6 July 2005 Page 5 of 6

6 4.24 Level (%) see section of the manual.. This is the level at which the measured voltage of any one phase of the three phase supply has to differ from the other phases before a fault is tripped. For example, if two phases are measured at 240VAC RMS, and the third phase is measured at 216VAC RMS, this is 10% error Operate delay(sec) see section of the manual. This is the time that a phase failure of the above magnitude must be present before a fault is tripped. Operate delay(sec) :->010 Reset Mode :Auto 5min Earth Fault Protn :Disabled 4.26 Reset Mode see section of the manual. The Reset Mode determines how the phase failure fault should be reset after it has been tripped, as per the reset mode for the locked rotor fault in step 4.11 of this document Earth Fault Protn see section of the manual. This fault compares the currents on all phases of the motor, and if one phase has increased relative to the other two phases, this is indicating that there is earth leakage, as the currents should always be balanced in a three-phase motor. Enabling this fault will cause a fault trip if the three measured currents on the three-phase supply are different by the level shown on the next screen Level (%) see section of the manual. This is the level at which the measured current of any one phase of the three phase supply has to differ from the other phases before a fault is tripped. For example, if two phases are measured at 100A RMS, and the third phase is measured at 110A RMS, this is 10% error. Note that this value is not editable here, as it is the same as the value set in step for the Phase Failure Fault. Setting the value in step sets the value for both the Phase Failure Fault and the Earth Fault Operate delay(sec) see section of the manual. This is the time that an earth fault of the above magnitude must be present before a fault is tripped. Level (%) :->25 Operate Delay(sec) :010 Reset Mode :Manual Reset Note: This value is not editable here, as it is the same as the value set in step 4.24 for the Phase Failure Fault. Setting the value in step 4.24 sets the value for both the Phase Failure Fault and the Earth Fault Reset Mode see section of the manual. The Reset Mode determines how the earth fault should be reset after it has been tripped, as per the reset mode for the locked rotor fault in step Conclusion This completes the parameters that need to be set up for motor protection on pump 1. Note that the procedure so far has only set up one motor. The other motors need the same information entered into them. If the motors are identical, or very similar, the easiest method of programming multiple motors is to program motor one first, then use the Copy Pump1 to Pump2 or Copy Pump1 to Pump3 options as shown in the Motor Protection Menu below. Selecting either of these functions will copy all of the motor protection parameters from the data stored for pump 1 to the next motor, which saves manually entering all of the data. Visit for the latest information.doc 6 July 2005 Page 6 of 6