Fuji FRENIC-Ace Drive Fault Codes:
| Fault Code | Cause & Solution |
|---|---|
| CoF PID feedback wire break | Cause: The signal line of PID feedback is broken. Solution: 1. The PID feedback signal wire is broken. – Check whether the PID feedback signal wires are connected correctly. – Check whether the PID feedback signal wires are connected correctly. Or, tighten the related terminal screws. – Check whether any contact part bites the wire sheath. 2. The inverter was affected by strong electrical noise. – Check whether appropriate noise control measures have been implemented (e.g. correct grounding and routing of signal wires, communications cables, and main circuit wires). – Implement noise control measures. – Separate the signal wires from the main power wires as far as possible. |
| dba Braking transistor error | Cause: A braking transistor error is detected. – The braking transistor is broken. Solution: – Check whether resistance of the braking resistor is correct or there is a misconnection of the resistor. |
| dbh Braking resistor overheated | Cause: Problem The electronic thermal protection for the braking resistor has been activated. Solution: 1. Braking load is too heavy. Reconsider the relationship between the estimated braking load and the real one. – Lower the real braking load. – Review the selection of the braking resistor and increase the braking capability. 2. Specified deceleration time is too short. Recalculate the deceleration torque and time needed for the load currently applied, based on a moment of inertia for the load and the deceleration time. – Increase the deceleration time . – Review the selection of the braking resistor and increase the braking capability. 3. Incorrect setting of function code data. Recheck the specifications of the braking resistor. |
| ECF EN circuit failure | Cause: Enable circuit state was diagnosed and a circuit failure was detected. Solution: 1. Contact defect on interface-PCB – Confirm that the interface-PCB is firmly mounted on the body. – Alarm is released by turning on again. 2. Enable circuit logic failure – Confirm that outputs from safety switch etc. are inputted by the same logic (High/High or Low/Low) with EN1 terminal/EN2 terminal. – Alarm is released by turning on again. 3. A failure (single failure) of enable circuit (safety stop circuit) was detected. – If the circuit failure is not removable by the procedures above, the inverter is out of order. |
| ECL Customizable logic failure | Cause: A setting failure of customizable logic was detected. Solution: 1. Setting of the selection of customizable logic operation was changed during operation. – Check whether the selection (Function code U00) of customizable logic operation is changed during operation. – Do not change the selection of customizable logic operation during operation to prevent a danger. |
| EF Ground fault | Cause: A ground fault current flew from the output terminal of the inverter. Solution: 1. Inverter output terminal(s) grounded (ground fault). – Disconnect the wiring from the output terminals [U], [V] and [W] and perform a Megger test for the inverter and the motor. – Remove the grounded parts (including replacement of the wires, relay terminals and motor). 2. The setting of the motor rated current (P04, A03, A103) is small relative to the inverter rated current. – Check whether an extremely small motor rated current is set relative to the inverter rated current. – Check the setting of the motor rated current (P04, A03, A103). – Disable the ground fault detection by setting “0” to the hundreds digit of H103 (Protection/maintenance function 1). |
| Er1 Memory error | Cause: Error occurred in writing the data to the memory in the inverter. Solution: 1. While the inverter was writing data (especially initializing data), power supply was turned off and the voltage for the control circuit dropped. – Check if pressing the PGR/RESET key resets the alarm after the function code data are initialized by setting the data of H03 to 1 – Return the initialized function code data to their previous settings, then restart the operation. 2. A high intensity noise was given to the inverter while data (especially initializing data) was being written. – Check if appropriate noise control measures have been implemented (e.g., correct grounding and routing of control and main circuit wires). – Improve noise control. Alternatively, return the initialized function code data to their previous settings, then restart the operation. 3. The control circuit failed. – Initialize the function code data by setting H03 to 1, then reset the alarm by pressing the PGR/RESET key and check that the alarm goes on. – This problem was caused by a problem of the printed circuit board (PCB) (on which the CPU is mounted). |
| Er2 Keypad communications error | Cause: A communications error occurred between the keypad and the inverter. Solution: 1. Break in the communications cable or poor contact. – Check continuity of the cable, contacts and connections. – Replace the cable. 2. A high intensity noise was given to the inverter. – Check if appropriate noise control measures have been implemented (e.g., correct grounding and routing of control and main circuit wires). – Improve noise control. 3. The remote keypad malfunctioned. – Check that alarm er2 does not occur if you connect another remote keypad to the inverter. – Replace the keypad. |
| Er3 CPU error | Cause: A CPU error (e.g. erratic CPU operation) occurred. Solution: 1. A high intensity noise was given to the inverter. – Check if appropriate noise control measures have been implemented (e.g. correct grounding and routing of control and main circuit wires). – Improve noise control. |
| Er4 Option card communications error | Cause: A communications error occurred between the option card and the inverter. Solution: 1. There was a problem with the connection between the bus option card and the inverter. – Check whether the connector on the bus option card is properly mating with the connector of the inverter. – Reload the bus option card into the inverter. 2. There was a high intensity noise from outside. – Check whether appropriate noise control measures have been implemented (e.g. correct grounding and routing of control and main circuit wires and communications cable). – Reinforce noise control measures. |
| Er5 Option card error | Cause: An error detected by the option card. Refer to the instruction manual of the option card for details. |
| Er6 Incorrect operation error | Cause: An error occurred due to incorrect operation of the motor. You incorrectly operated the inverter. Solution: 1. The STOP key was pressed when H96 = 1 or 3. Even though a run command was present at the input terminal or the communication port, the inverter was forced to decelerate to stop and er6 was displayed. – If this was not intended, check the setting of H96. 2. The start check function was activated when H96 = 2 or 3. When one of the following conditions occurred while a run command was present at the input, the inverter did not run and er6 was displayed: – The power was switched on – An alarm was released Review the running sequence to avoid input of the run command when er6 has occurred. |
| Er7 Tuning error | Cause: Auto-tuning failed. Solution: 1. A phase was missing (There was a phase loss) in the connection between the inverter and the motor. – Properly connect the motor to the inverter. 2. V/f or the rated current of the motor was not properly set. 3. The connection between the inverter and the motor was too long. – Check whether the connection length between the inverter and the motor is not exceeding 50m. – Review, and if necessary, change the layout of the inverter and the motor to shorten the connection wire. 4. The rated capacity of the motor was significantly different from that of the inverter. – Check whether the rated capacity of the motor is smaller than that of the inverter by three or more orders of class or larger by two or more orders of class. – Check whether it is possible to replace the inverter with one with an appropriate capacity. 5. The motor was a special type such as a high-speed motor. |
| Er8 RS-485 communications error | Cause: A communications error occurred during RS-485 communications. Solution: 1. Host controllers (e.g., PLCs and personal computers) did not operate due to incorrect settings and/or defective software/hardware. – Check the controllers. – Remove the cause of the controller error. 2. RS-485 converter did not operate due to incorrect connections and settings, or hardware defective. – Check the RS-485 converter (e.g., check for poor contact). – Change the various RS-485 converter settings, reconnect the wires, or replace the converter with a recommended device as appropriate. 3. Broken communications cable or poor contact. – Check continuity of the cable, contacts and connections. – Replace the cable. 4. Even though no response error detection time has been set, communications did not occur cyclically. – Check the host controllers. – Change the settings of host controller software, or make the no response error detection time invalid. 5. A high intensity noise was given to the inverter. – Check if appropriate noise control measures have been implemented (e.g., correct grounding and routing of control and main circuit wires). – Improve noise control. – Improve noise reduction measures on the host side. – Replace the relay converter with a recommended insulated converter. |
| ErP RS-485 communications error | Cause: A communications error occurred during RS-485 communications. Solution: 1. Host controllers (e.g., PLCs and personal computers) did not operate due to incorrect settings and/or defective software/hardware. – Check the controllers. – Remove the cause of the controller error. 2. RS-485 converter did not operate due to incorrect connections and settings, or hardware defective. – Check the RS-485 converter (e.g., check for poor contact). – Change the various RS-485 converter settings, reconnect the wires, or replace the converter with a recommended device as appropriate. 3. Broken communications cable or poor contact. – Check continuity of the cable, contacts and connections. – Replace the cable. 4. Even though no response error detection time has been set, communications did not occur cyclically. – Check the host controllers. – Change the settings of host controller software, or make the no response error detection time invalid. 5. A high intensity noise was given to the inverter. – Check if appropriate noise control measures have been implemented (e.g., correct grounding and routing of control and main circuit wires). – Improve noise control. – Improve noise reduction measures on the host side. – Replace the relay converter with a recommended insulated converter. |
| Erd Step-out detection /detection failure of magnetic pole position at startup | Cause: The step-out of PM motor was detected. The magnetic pole position at startup failed to be detected. Solution: 1. Function code settings do not agree with the motor characteristics. – Check whether F04, F05, P01, P02, P03, P60, P61, P62, P63, P64 agree with the motor constants. – Perform auto-tuning of the inverter for every motor to be used. 2. Magnetic pole position detection method is not appropriate. – Confirm that the magnetic pole position detection mode matches the motor type. – Match the magnetic pole position detection mode selection (P30) to the motor type. 3. Starting frequency (continuation time) (F24) is insufficient. – Check whether a starting frequency (continuation time) (F24) is set optimally, after setting the magnetic pole position detection mode selection (P30) to “0” or “3.” – Set a period of time during which motor can rotate by one or more revolutions. F24P01/2/F23 (P01: Number of poles, F23: Starting frequency) 4. Starting torque is insufficient. Check the data of acceleration times (F07, E10, E12, E14) and a current command value on a start (P74). – Change the acceleration time to match the load. – Increase the current command value at startup. 5. Load is small. Check the data of a reference current at starting (P74). – Decrease the reference current at starting. – Set it to 80% or lower when running a motor single unit in a test run etc. |
| ErE Speed inconsistency Excessive speed deviation | Cause: An excessive deviation appears between the speed command and the detected speed. Solution: 1. Incorrect setting of function code data. – Check the motor parameter “Number of poles” (P01*). – Specify the P01* data in accordance with the motor to be used. 2. Overload. Measure the inverter output current. – Reduce the load. – Check whether any mechanical brake is applied. – Release the mechanical brake. 3. The motor speed does not increase due to the current limiter operation. – Check the data of function code F44 (Current limiter (Level)). – Change the F44 data correctly. Or, set the F43 data to “0” (Disable) if the current limiter operation is not needed. – Check the data of the function codes (F04*, F05*, P01*-P12*) to see if V/f is set correctly. – Match the V/f pattern setting with the motor ratings. – Change the function code data in accordance with the motor parameters. 4. Function code settings do not match the motor characteristics. – Confirm that P01*, P02*, P03*, P06*, P07*, P08*, P09*, P10*, P12* match the motor constants. – Perform auto-tuning of the inverter, using the function code P04*. 5. Wiring to the motor is incorrect. Check the wiring to the motor. – Connect the inverter output terminals U, V, and W to the motor input terminals U, V, and W, respectively. 6. The motor speed does not increase due to the torque limiter operation. – Check the data of F40 (Torque limiter (Level)). – Change the F40 data correctly. Or, set the F40 data to “999” (Disable) if the torque limiter operation is not needed. 7. The wire between the pulse generator (PG) and the option card is broken or incorrect. – Check whether the pulse generator (PG) is correctly connected to the option card or any wire is broken. – Check whether the PG is connected correctly. Or, tighten the related terminal screws. |
| ErF Data save error during undervoltage | Cause: The inverter was unable to save data such as the frequency commands, timer operation time, and PID process command set through the keypad when the power was switched off. Solution: 1. The control circuit voltage dropped suddenly while data was being saved when the power was turned off, because the DC link bus was rapidly discharged. – Check how long it takes for the DC link bus voltage to drop to the preset voltage when power is turned off. – Remove whatever is causing the rapid discharge of the DC link circuit. After pressing the PGR/RESET key and releasing the alarm, set, using a remote keypad, the data of the relevant function codes (such as the frequency commands, timer operation time, and PID process command) back to the original values and then restart the operation. 2. A high intensity noise affected the operation of the inverter while data was being saved when the power was turned off. – Check if appropriate noise control measures have been implemented (e.g., correct grounding and routing of control and main circuit wires). – Improve noise control. After pressing the PGR/RESET key and releasing the alarm, set, using a remote keypad, the data of the relevant function codes (such as the frequency commands, timer operation time, and PID process command) back to the original values and then restart the operation. 3. The control circuit failed. Check if erf occurs each time power is switched off. – This problem was caused by a problem of the printed circuit board (PCB) (on which the CPU is mounted). |
| ErH Hardware error | Cause: An error occurred in the LSI on the power printed circuit board (power PCB). Solution: 1. The capacity is not set properly on the control printed circuit board. – The inverter capacity needs to be modified again. 2. The contents of the memory on the power supply printed circuit board are corrupted. – The power supply printed circuit board needs to be replaced. 3. Connection problem between the control printed circuit board and the power supply printed circuit board – Either the control printed circuit board or the power supply printed circuit board needs to be replaced. |
| Ero Positioning control error | Cause: Excessive position deviation occurred on servo lock / position control. Solution: 1. Insufficient gain in positioning control system (servo lock) – Readjust the settings of J97 (Servo lock (Gain)) and d03 (Speed control 1 P (Gain)). 2. Incorrect control completion width (servo lock) – Check whether the setting of J99 (Servo lock (Completion range)) is correct. – Correct the setting of J99. 3. Position deviation is excessive. (servo lock) – Check whether the excessive error detection level (d78) is set up properly. 4. Position deviation is excessive. (position control) – The position feedback pulses are not received. – Check whether the PG is connected correctly. Or, tighten the related terminal screws. – Check whether any contact part bites the wire sheath. – Replace the wire / pulse generator. |
| Err Simulated failure | Cause: The LED displays the alarm err. Solution: 1. Keep key STOP + FUNC/Data key pressed for five seconds or longer. – To escape from this alarm state, press the PGR/RES key. |
| Ert CAN communications failure | Cause: Communications error occurred in CAN bus communications. Solution: 1. Baud rate settings differ. Check the data of baud rate (y24) and setting details of host equipment side. – Correct any settings that differ. 2. Defect of host controllers (including programmable controller, personal computer, etc.) (Defects of control software, setting and hardware) – Check the host equipment. – Remove the cause of the equipment error. 3. Break and contact failure of communications cables – Check the continuity of the cables, contacts and connections. – Replace the cable. 4. The inverter was affected by strong electrical noise. – Check if appropriate noise control measures have been implemented (e.g., correct grounding and routing of communications cables and main circuit wires). – Implement noise control measures. – Implement noise reduction measures on the host side. |
| FUS/FU5 DC Fuse blown | Cause: The fuse inside the inverter blew. Solution: 1. The fuse blew because of a short-circuiting inside the inverter. – Check whether there has been any excess surge or noise coming from outside. – Take measures against surges and noise. – Have the inverter repaired. |
| Lin Input phase loss | Cause & Solution: 1. Three phase input is abnormal. – Eliminate faults in external circuitry 2. Drive board is abnormal. – Eliminate faults in external circuitry 3. Lightning protection board is abnormal. – There is an hardware or software issue in drive. Need to repair or replace drive. 4. Control board is abnormal. – There is an hardware or software issue in drive. Need to repair or replace drive. |
| LU/LV Undervoltage | Cause & Solution: 1. An instantaneous power failure occurs. – Reset the fault 2. The AC drive’s input voltage is not within the permissible range. – Adjust the voltage to normal range. 3. The bus voltage is abnormal. – Replace the AC drive. 4. The rectifier bridge, the pre-charge resistor, the drive board or the control board are abnormal. – Replace the AC drive. |
| OCn Overcurrent | Cause & Solution: 1. Ground fault or short circuit exists in the output circuit. – Check whether short-circuit occurs on the motor, the motor cable or contactor. 2. Acceleration time is too short. – Increase acceleration time. 3. Customized torque boost or V/F curve is not appropriate. – Adjust the customized torque boost or V/F curve. 4. The voltage is too low. – Adjust the voltage to normal range. 5. The spinning motor is started. – Enable the catching a spinning motor function or start the motor after it stops. 6. A load is applied suddenly during acceleration. – Cancel the suddenly added load. 7. The rated AC drive power is low. – Replace the drive by one with higher rated power. 8. The braking resistor resistance is small. – The braking resistor is short circuited. – Replace a new braking resistor. |
| OC1 Overcurrent during acceleration | Cause & Solution: 1. Ground fault or short circuit exists in the output circuit. – Check whether short-circuit occurs on the motor, the motor cable or contactor. 2. Acceleration time is too short. – Increase acceleration time. 3. Customized torque boost or V/F curve is not appropriate. – Adjust the customized torque boost or V/F curve. 4. The voltage is too low. – Adjust the voltage to normal range. 5. The spinning motor is started. – Enable the catching a spinning motor function or start the motor after it stops. 6. A load is applied suddenly during acceleration. – Cancel the suddenly added load. 7. The rated AC drive power is low. – Replace the drive by one with higher rated power. 8. The braking resistor resistance is small. – The braking resistor is short circuited. – Replace a new braking resistor. |
| OC2 Overcurrent during deceleration | Cause & Solution: 1. Ground fault or short circuit exists in the output circuit. – Check whether short-circuit occurs on motor, motor cable or contactor. 2. Acceleration time is too short. – Increase acceleration time. 3. The voltage is too low. – Adjust the voltage to normal range. 4. A load is added suddenly during deceleration. – Cancel the suddenly added load. 5. Braking unit and braking resistor are not installed. – Install the braking unit and braking resistor. 6. The braking resistor resistance is small or the braking resistor is short circuited. – Replace a new braking resistor. |
| OC3 Overcurrent at constant speed | Cause & Solution: 1. Ground fault or short circuit exists in the output circuit. – Check whether short-circuit occurs on the motor, motor cable or contactor 2. The voltage is too low. – Adjust the voltage to normal range. 3. A load is added suddenly during running. – Cancel the suddenly added load. 4. The rated AC drive power is low. – Replace the drive by one with higher rated power. 5. The braking resistor resistance is small or the braking resistor is short circuited. – Replace a new braking resistor. |
| OH1 Heat sink overheat | Cause & Solution: 1. The ambient temperature is too high. – Lower the ambient temperature. 2. The ventilation is clogged. – Clean the ventilation. 3. The fan is damaged. – Replace the cooling fan. 4. The thermally sensitive resistor of IGBT is damaged. – Replace the AC drive. 5. The AC drive IGBT is damaged. – Replace the AC drive. |
| OH2 External alarm input | Cause: External alarm was inputted (THR). Solution: 1. An alarm function of the external equipment was activated. – Inspect external equipment operation. – Remove the cause of the alarm that occurred. 2. Connection has been performed incorrectly. – Check if the wire for the external alarm signal is correctly connected to the terminal to which the “Alarm from external equipment” has been assigned. – Connect the wire for the alarm signal correctly. 3. Incorrect settings. – Check if the “Alarm from external equipment” has not been assigned to an unassigned terminal. – Correct the assignment. |
| OH3 Inverter Internal overheat | Cause: The temperature inside the inverter exceeded the allowable limit. Solution: 1. The ambient temperature exceeded the allowable limit specified for the inverter. – Measure the ambient temperature. – Lower the ambient temperature by improving the ventilation. |
| OH4 Motor overheat (PTC/NTC thermistor) | Cause: Temperature of the motor has risen abnormally. Solution: 1. The temperature around the motor exceeded the range of the motor specification. – Measure the temperature around the motor. 2. Cooling system for the motor defective. – Check if the cooling system of the motor is operating normally. 3. The activation level of the PTC thermistor for motor overheat protection was set inadequately. – Check the PTC thermistor specifications and recalculate the detection voltage. 4. Settings for the PTC/NTC thermistor are improper. – Check the setting of the thermistor mode selection. |
| OH6 Charging resistor overheat | Cause: Temperature of the charging resistor inside the inverter has risen abnormally. Solution: 1. The inverter power is turned ON and OFF frequently. – Suppress the inverter power ON/OFF cycles. – Turn ON and OFF the inverter power once or less per 30 min. 2. The inverter power is not turned ON and OFF frequently. – Check that this alarm always occurs when the inverter power is turned ON. – The charging circuit of the inverter is faulty. |
| OLn Overload of motor 1 through 3 | Cause: Electronic thermal protection for motor 1, 2, or 3 activated. Solution: 1. The electronic thermal characteristics do not match the motor overload characteristics. – Check the motor characteristics. 2. The activation level for the electronic thermal protection was not appropriate. – Check the continuous allowable current of the motor 3. The specified acceleration/ deceleration time was too short. – Recalculate the acceleration/deceleration torque and time needed for the load, based on the moment of inertia for the load and the acceleration/deceleration time. 4. Overload. – Measure the output current. |
| OL1 Motor 1 overload | Cause: Electronic thermal protection for motor 1 activated. Solution: 1. The electronic thermal characteristics do not match the motor overload characteristics. – Check the motor characteristics. 2. The activation level for the electronic thermal protection was not appropriate. – Check the continuous allowable current of the motor 3. The specified acceleration/ deceleration time was too short. – Recalculate the acceleration/deceleration torque and time needed for the load, based on the moment of inertia for the load and the acceleration/deceleration time. 4. Overload. – Measure the output current. |
| OL2 Motor 2 overload | Cause: Electronic thermal protection for motor 2 activated. Solution: 1. The electronic thermal characteristics do not match the motor overload characteristics. – Check the motor characteristics. 2. The activation level for the electronic thermal protection was not appropriate. – Check the continuous allowable current of the motor 3. The specified acceleration/ deceleration time was too short. – Recalculate the acceleration/deceleration torque and time needed for the load, based on the moment of inertia for the load and the acceleration/deceleration time. 4. Overload. – Measure the output current. |
| OLU Inverter overload | Cause & Solution: Temperature inside inverter rose abnormally. 1. The load is too heavy or locked-rotor occurs on the motor. – Reduce the load or check motor and mechanical conditions. 2. The rated AC drive power is low. – Replace the drive by one with higher rated power. 3. Temperature around the inverter exceeded that of inverter specifications. – Measure the temperature around the inverter. |
| OPL Output phase loss | Cause & Solution: 1. Motor winding is damaged. Check resistance between motor cables. – Replace motor is winding is damaged. 2. The cable connecting the AC drive and the motor is abnormal. – Check for wiring errors and ensure the output cable is connected properly 3. The AC drive’s three-phase outputs are unbalanced when the motor is running. – Check whether the motor three-phase winding is normal. 4. The drive board or the IGBT is abnormal. – Replace the AC drive. |
| OS/O5 Overspeed | Cause: Motor rotated at excessive speed (When motor speed>(F03×1.2)). Solution: Incorrect setting of function code data. 1. Check the motor parameter “Number of poles” setting (P01). – Specify the P01 data in accordance with the motor to be used. 2. Check the maximum frequency setting (F03). – Specify the F03 data in accordance with the output frequency. |
| OUn Overvoltage | Cause & Solution: 1. Input voltage is too high. – Adjust input voltage to normal range. 2. An external force drives motor during acceleration. – Cancel the external force. 3. Braking unit and braking resistor are not installed. – Install the braking unit and braking resistor. 4. Acceleration time is too short. – Increase acceleration time. |
| OV1/OU1 Overvoltage during acceleration | Cause & Solution: 1. Input voltage is too high. – Adjust input voltage to normal range. 2. An external force drives motor during acceleration. – Cancel the external force. 3. Braking unit and braking resistor are not installed. – Install the braking unit and braking resistor. 4. Acceleration time is too short. – Increase acceleration time. |
| OV2/OU2 Overvoltage during deceleration | Cause & Solution: 1. Input voltage is too high. – Adjust input voltage to normal range. 2. An external force drives motor during deceleration. – Cancel the external force or install the braking resistor. 3. Deceleration time is too short. – Increase deceleration time. 4. Braking unit and braking resistor are not installed. – Install the braking unit and braking resistor. |
| OV3/OU3 Overvoltage at constant speed | Cause & Solution: 1. Input voltage is too high. – Adjust input voltage to normal range. 2. An external force drives motor during running. – Cancel the external force or install a braking resistor. |
| PbF Charger circuit fault | Cause: The magnetic contactor for short-circuiting the resistor for charging failed to work. Solution: Control power was not supplied to the magnetic contactor intended for short-circuiting the charging resistor. 1. Check whether, in normal connection of the main circuit (not connection via the DC link bus), the connector on the power supply printed circuit board is not inserted to NC . – Insert the connector to FAN . 2. Check whether you have quickly turned the circuit breaker ON and OFF to confirm safety after cabling/wiring. – Wait until the DC link bus voltage has dropped to a sufficiently low level and then reset the current alarm, and turn ON the power again. (Do not turn the circuit breaker ON and OFF quickly.) (Turning ON the circuit breaker supplies power to the control circuit to the operation level (lighting LEDs on the keypad) in a short period. Immediately turning it OFF even retains the control circuit power for a time, while it shuts down the power to the magnetic contactor intended for short-circuiting the charging resistor since the contactor is directly powered from the main power. – Under such conditions, the control circuit can issue a turn-on command to the magnetic contactor, but the contactor not powered can produce nothing. This state is regarded as abnormal, causing an alarm.) |