Baldor VFD Fault Codes

Invalid Base ID: Failure to determine control horsepower and input voltage configuration from the Power Base ID value in software

What it means: The control board cannot work out the horsepower and input voltage of the power section it is fitted to, because it does not recognize the Power Base ID.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Control does not recognize the hp and voltage configuration of the power base

First checks, in this order

1. Press RESET on the keypad.
2. If the fault remains, open Diagnostic Info and compare the reported power base ID with Table 5-2 Power Base ID in MN715 for your catalog number.
3. If the ID is different from the table, call Baldor.

NV Memory Fail: Failure to read or write to non-volatile memory

What it means: The control could not read from or write to its non-volatile memory, where the parameter settings are kept.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Memory fault in the control

First checks, in this order

1. Press RESET on the keypad.
2. Restore the parameter values to factory settings, then re-enter your own settings.
3. If the fault remains, call Baldor.

Param Checksum: Parameter Checksum error detected

What it means: The checksum of the stored parameters does not match, so the parameter data may be corrupt.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Memory fault in the control

First checks, in this order

1. Press RESET on the keypad.
2. Restore the parameter values to factory settings, then re-enter your own settings.
3. If the fault remains, call Baldor.

Low INIT Bus V: Low bus voltage detected on startup

What it means: When power was applied, the DC bus did not charge to a high enough voltage.^[1][2][5][3]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Improper (low) AC line voltage (cause given for the same message in the Series 18H manual MN718)

First checks, in this order

1. Check the input AC voltage level at the control.
2. Disconnect the dynamic brake hardware and retry (corrective action printed for the same message in MN718).
3. Check that the supply matches the model voltage range, for example 180 to 264 VAC 3 phase 60 Hz on 230 VAC models and 342 to 528 VAC 3 phase 60 Hz on 460 VAC models (MN715 specifications).

HW Desaturation: High output current condition detected (greater than 400% of rated output current)

What it means: Output current spiked above about 400% of the control's rated output current and the hardware desaturation protection tripped. On size B2 controls Baldor says a desat error can also mean low line impedance, a brake transistor failure or an internal output transistor overtemperature.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Accel or Decel rate set too short
• Torque Boost set too high
• Electrical noise in the logic circuits
• Motor overloaded
• Size B2 controls: low line impedance, brake transistor failure or output transistor overtemperature

First checks, in this order

1. Lengthen the Accel and Decel rates.
2. Reduce the torque boost value.
3. Check grounding of the power wiring and shielding of the signal wiring.
4. Verify the control and motor are sized correctly, or reduce the motor load.
5. On size B2 controls check the supply line impedance: MN715 asks for 1% minimum on B2, C2, D2, F, G, G2, G+ and H sizes and 3% minimum on A, B, C, D and E sizes.

HW Surge Current: High output current condition detected (greater than 250% of rated output current)

What it means: Output current went above about 250% of the control's rated output current.^[1][2][5][6]

Also on: 15V (MN715V lists the same message and description). Series 15J (MN715J) lists the same message and description; the checks above are the corrective actions MN715J prints for it.

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Output current surge, for example while the motor is ramping (motor, coupling or load problem)
• Accel time too short
• Torque boost set wrong

First checks, in this order

1. Turn power off and on (cycle power).
2. If it tripped while ramping the motor, check the motor, the coupling and the load.
3. Increase the Accel time.
4. Increase or decrease the torque boost value.
5. Press RESET. If the fault remains, contact Baldor.

HW Ground Fault: Ground Fault detected (output current leakage to ground)

What it means: Motor current is leaking to ground somewhere in the motor leads or inside the motor.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Output (motor) current leakage to ground
• Motor internally shorted to ground
• Motor lead wire with high capacitance

First checks, in this order

1. Disconnect the wiring between the control and the motor and retry the test.
2. If the fault clears, reconnect the motor leads and retry. Repair the motor if it is internally shorted.
3. Replace the motor lead wire with low capacitance cable.
4. If the ground fault remains with the motor disconnected, contact Baldor.
5. Before any Megger (insulation) test on the motor, disconnect motor leads T1, T2 and T3 from the control, or the control will be badly damaged.

HW Power Supply: Control Board power supply failure detected

What it means: The power supply that feeds the control board has failed.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Power supply malfunction

First checks, in this order

1. With power removed and the 5 minute discharge wait done, check the internal connections.
2. Baldor's corrective action is to replace the logic power board.

Hardware Protect: A general hardware fault was detected but cannot be isolated

What it means: The control saw a hardware fault but it lasted too short a time to tell which one.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Fault duration too short to be identified

First checks, in this order

1. Reset the control.
2. Check grounding of the power wiring and shielding of the signal wiring.
3. If the fault keeps returning, Baldor's corrective action is to replace the control board.

1 MIN Overload: Peak output current exceeded the 1 minute rating value

What it means: Output current stayed above the 1 minute overload rating for too long. MN715 rates overload capacity at 150% for 60 seconds in Constant Torque mode and 115% for 60 seconds in Variable Torque mode.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Motor overloaded
• PK Current Limit setting
• ACCEL or DECEL times too short
• Control and motor not sized for the load

First checks, in this order

1. Check the PK Current Limit parameter in the Level 2 Output Limits block.
2. Check the motor for overloading.
3. Increase the ACCEL and DECEL times.
4. Reduce the motor load.
5. Verify the control and motor are sized correctly.
6. Diagnostic Info shows the % overload current remaining.

3 SEC Overload: Peak output current exceeded the 3 second rating value

What it means: Output current went above the short time peak rating. MN715 rates it at 170 to 200% for 3 seconds in Constant Torque mode.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Motor overloaded
• PK Current Limit setting
• ACCEL time too short
• Control and motor not sized for the load

First checks, in this order

1. Check the PK Current Limit parameter in the Level 2 Output Limits block.
2. Check the motor for overloading.
3. Increase the ACCEL time.
4. Reduce the motor load.
5. Verify the control and motor are sized correctly.

Overcurrent: Continuous current limit exceeded

What it means: Output current stayed above the control's continuous current limit.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Load current above the continuous rating of the control

First checks, in this order

1. Read the fault log to see when it tripped and which faults came with it.
2. Check the motor for overloading and verify the control and motor are sized correctly (Baldor's corrective action for the 15H overload messages).
3. Check that all power and control wiring is correct and installed as the manual recommends before contacting Baldor.

BUS Overvoltage: High DC Bus voltage

What it means: The DC bus voltage went too high, usually from energy coming back from the motor while it slows down. The 15H troubleshooting table lists this indication as Bus Overvoltage Trip or HW Overvoltage.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Excessive dynamic braking power
• DECEL rate set too low a value (decel too fast)
• Overhauling motor load
• Dynamic brake miswired
• Input voltage too high

First checks, in this order

1. Check the dynamic brake watt and resistance parameter values.
2. Lengthen the DECEL time.
3. Add external dynamic braking: an RGA resistor kit or an RBA transistor assembly.
4. Correct the problem with the overhauling motor load.
5. Check the dynamic brake hardware wiring.
6. Verify the AC line voltage. Use a step down transformer if needed and a line reactor to minimize spikes.

Bus Undervoltage: Low DC Bus voltage condition detected

What it means: The DC bus voltage dropped too low, usually because the AC supply sagged or is too low.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Input voltage too low
• Power line sags, for example when other equipment starts

First checks, in this order

1. Verify the AC line voltage. Use a step up transformer if needed.
2. Check for power line disturbances such as sags caused by other equipment starting.
3. Monitor the power line with a date and time imprint to isolate the power problem.
4. Disconnect the dynamic brake hardware and repeat the operation.

Heat Sink Temp: Control heatsink exceeded upper temperature limit

What it means: The control's heatsink got too hot. On size B2 controls the main heatsink or the gate drive circuit board may be too hot.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Motor overloaded
• Ambient temperature too high
• Built in fans ineffective or not running

First checks, in this order

1. Correct the motor loading and verify the control and motor sizing.
2. Move the control to a cooler area, or add cooling fans or air conditioning to the cabinet. MN715 rates the control for 0 to 40 degrees C, derated 2% per degree C above 40 up to 55 degrees C maximum.
3. Verify the fans run, remove debris from the fan and heatsink surfaces, and replace the fan or check fan wiring.
4. Diagnostic Info shows the control temperature in degrees C.

External Trip: Connection between J4-16 and J4-17 is open

What it means: The external trip input (usually the motor thermostat) opened. With Level 2 Protection block External Trip set to ON, opening the normally closed contact at J4-16 (to J4-17) shuts the drive down.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: the control disables and the motor coasts to a stop; the fault is logged

Likely causes

• Motor ventilation insufficient
• Motor drawing excessive current
• Volts/Hertz ratio wrong
• No thermostat connected
• Poor thermostat connections
• External Trip parameter set ON with nothing wired to J4-16

First checks, in this order

1. Clean the motor air intake and exhaust, check the external blower and verify the motor's internal fan is coupled securely.
2. Check the motor for overloading and verify the control and motor sizing.
3. Adjust the Volts/Hz parameter, the Base Frequency and the Max Output Voltage.
4. Connect the thermostat and verify all external trip circuits used with it, or disable the thermostat input at the control.
5. Check the thermostat connections.
6. If nothing is wired to J4-16, set External Trip to OFF.

New Base ID: Control board detected a change in the Power Base ID value in software

What it means: The control board found itself on a different power base than before, typically after a control board or circuit board was replaced.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Control or circuit board replaced

First checks, in this order

1. Restore the parameters to factory settings.
2. Reset the control.
3. Then re-enter your application settings.

REGEN RES Power: Excessive power dissipation required by Dynamic Brake Hardware

What it means: The braking energy the drive has to dump into the dynamic brake resistor is more than the resistor rating set in the control.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Incorrect dynamic brake parameter
• Regen power exceeded the dynamic brake resistor rating

First checks, in this order

1. Check the Resistor Ohms and Resistor Watts parameters in the Level 2 Brake Adjust block.
2. Add external dynamic braking: an RGA resistor kit or an RBA transistor assembly.
3. Increase the Decel Time.

EXB Selection: Expansion board not installed to support the selected Level 1 Input Block, Command Select parameter

What it means: The operating mode chosen in Command Select needs an expansion board that is not fitted. The 15H troubleshooting table lists this under the indication Command Select.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Incorrect operating mode programmed
• Expansion board needed for the selected mode is not installed

First checks, in this order

1. Change the Operating Mode in the Level 1 Input block to one that does not require the expansion board.
2. Or install the correct expansion board for the selected operating mode.
3. Diagnostic Info shows which Group 1 or Group 2 expansion boards are installed.

Torque Proving: Unbalanced current in the three phase motor leads

What it means: The output current in the three motor phases is not balanced, which can mean an open phase or a bad connection between the drive and the motor.^[1][2][5][3]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Unbalanced current in the 3 motor phases

First checks, in this order

1. Check continuity from the control to the motor windings and verify the motor connections (corrective action printed for the matching Torque Prove FLT message in MN718).

Unknown FLT Code: Microprocessor detected a fault that is not identified in the fault code table

What it means: The control logged a fault that is not in its fault code table.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Microprocessor detected a fault that is not defined in the fault code table

First checks, in this order

1. Press RESET on the keypad.
2. Restore the parameter values to factory settings.
3. If the fault remains, call Baldor.

µP RESET: A software watchdog timer has reset the processor because a process has timed out

What it means: The microprocessor was restarted by its own watchdog because a software process took too long. On the 18H the similar message means something else, see that row.^[1][2][5]

Also on: 15V (MN715V lists the same message and description). The 15H troubleshooting table prints it as uP Reset.

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Software process timed out

First checks, in this order

1. Press RESET on the keypad.
2. If the fault remains, call Baldor.

FLT Log MEM Fail: Corrupt data in fault log (may occur on older systems only)

What it means: The fault log memory holds corrupt data.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Corrupt data in the fault log, mainly on older systems

First checks, in this order

1. Press RESET on the keypad.
2. If the fault remains, call Baldor.

Current SENS FLT: Failure to sense phase current

What it means: The control cannot read the output phase current.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Phase current sensing failure

First checks, in this order

1. Press RESET on the keypad.
2. If the fault remains, call Baldor.

Bus Current SENS: Failure to sense bus current

What it means: The control cannot read the DC bus current.^[1][2][5]

Also on: 15V (MN715V lists the same message and description)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Bus current sensing failure

First checks, in this order

1. Press RESET on the keypad.
2. If the fault remains, call Baldor.

Over Speed: Motor exceeded 110% of MAX Output Freq parameter value

What it means: Output frequency went above 110% of the maximum output frequency set in the control.^[1][2][5]

Also on: 15V (the MN715V troubleshooting table prints the same indication)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Motor driven above 110% of the MAX Output Freq setting

First checks, in this order

1. Check Max Output Freq in the Level 2 Output Limits block.

Current Sens FLT: Defective phase current sensor or open circuit detected between control board and current sensor

What it means: The control lost the signal from a phase current sensor, either because the sensor failed or because its connection to the control board is open.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Open circuit between the control board and the current sensor
• Defective current sensor

First checks, in this order

1. With power off and the 5 minute discharge wait done, check the connections between the control board and the current sensor.
2. Replace the current sensor if it is defective.

DC Bus High: Bus over voltage condition occurred

What it means: The DC bus voltage went too high, usually from braking energy coming back from the motor or a high supply voltage.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Excessive dynamic braking power
• Dynamic brake miswiring
• Input voltage too high
• Decel rate too fast (listed in the 23H manual)

First checks, in this order

1. Increase the DECEL time.
2. Check the dynamic brake watt and resistance parameter values.
3. Add optional dynamic braking hardware.
4. Check the dynamic brake hardware wiring.
5. Verify the AC line voltage. Use a step down isolation transformer if needed and a line reactor to minimize spikes.

DC Bus Low: Bus under voltage condition occurred

What it means: The DC bus voltage dropped too low, usually because the AC supply is low or sagged.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Input voltage too low
• Power line sags, for example when other equipment starts

First checks, in this order

1. Verify the AC line voltage. Use a step up isolation transformer if needed.
2. Check for power line disturbances such as sags caused by other equipment starting.
3. Monitor the power line with a date and time imprint to isolate the power problem.
4. Disconnect the dynamic brake hardware and repeat the operation.

Encoder Loss: Noise on encoder lines, encoder power supply loss, encoder coupling slipping or broken, defective encoder or defective wiring

What it means: The control lost a valid encoder feedback signal from the motor.^[3]

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Encoder power supply failure
• Encoder coupling slipping, broken or misaligned
• Excessive noise on the encoder lines
• Defective encoder or defective wiring

First checks, in this order

1. Check for 5 VDC at J1-29 and J1-30, and for +5 VDC and ground at the encoder end pins.
2. Correct or replace the encoder to motor coupling.
3. Check the position counter in Diagnostic Information for jittering, which confirms an encoder problem.
4. Check the encoder connections, separate the encoder leads from power wiring and cross encoder and power wires at 90 degrees.
5. Electrically isolate the encoder from the motor, or install the optional Isolated Encoder Feedback expansion board.

External Trip: An external over temperature condition occurred or open circuit on J1-16

What it means: The external trip input (usually the motor thermostat) opened. With Level 2 Protection block External Trip set to ON, opening the normally closed contact at J1-16 shuts the drive down.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: the control disables and the motor coasts to a stop; the fault is shown and logged

Likely causes

• Motor ventilation insufficient
• Motor drawing excessive current
• No thermostat connected
• Poor thermostat connections
• External Trip parameter set ON with nothing wired to J1-16

First checks, in this order

1. Clean the motor air intake and exhaust, check the external blower and verify the motor's internal fan is coupled securely.
2. Check the motor for overloading and verify the control and motor sizing.
3. Connect the thermostat and verify all external trip circuits used with it, or disable the thermostat input at J1-16.
4. Check the thermostat connections.
5. If nothing is wired to J1-16, set External Trip to OFF in the Level 2 Protection block.
6. Use a dry contact thermostat that needs no external power; power on the J1-16 and J1-17 leads can damage the control.

Following Error: Excessive following error detected between command and feedback signals

What it means: Actual speed fell outside the allowed band around the commanded speed. This trip only happens when Following Error is ON in the Level 2 Protection block; the band is the Level 1 Output block AT Speed Band.^[3]

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Speed proportional gain set too low
• Current limit set too low
• ACCEL or DECEL time too short
• Excessive load

First checks, in this order

1. Increase the Speed PROP Gain parameter.
2. Increase the Current Limit parameter.
3. Increase the ACCEL and DECEL times.
4. Verify the control and motor are sized correctly for the load.
5. Check the AT Speed Band setting in the Level 1 Output block.

GND FLT: Low impedance path detected between an output phase and ground

What it means: One of the output phases has a low resistance path to ground, in the wiring or in the motor.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Improper wiring
• Wiring shorted in the conduit
• Motor winding shorted

First checks, in this order

1. Disconnect the wiring between the control and the motor and retry the test.
2. If GND FLT clears, reconnect the motor leads and retry. Rewire as necessary or repair the motor.
3. If GND FLT remains with the motor disconnected, contact Baldor.
4. Before any Megger (insulation) test on the motor, disconnect motor leads T1, T2 and T3 from the control, or the control will be badly damaged.

INT Over-Temp: Temperature of control heatsink exceeded safe level

What it means: The control's heatsink got too hot.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Motor overloaded
• Ambient temperature too high
• Cooling fans clogged or air path restricted (listed in the 23H manual)

First checks, in this order

1. Correct the motor loading and verify the control and motor sizing.
2. Move the control to a cooler area, or add cooling fans or air conditioning to the cabinet. MN718 rates the control for minus 10 to plus 40 degrees C, derated 2% per degree C above 40 up to 55 degrees C maximum.
3. Clean the fans and the air path.
4. Diagnostic Info shows the control temperature.

Invalid Base ID: Control does not recognize power base ID

What it means: The control board does not recognize the horsepower and voltage configuration of the power base it is fitted to.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Control does not recognize the HP and voltage configuration

First checks, in this order

1. Press RESET on the keypad.
2. If the fault remains, call Baldor.
3. Diagnostic Info shows the power base ID as a hexadecimal value; Table 5-3 of MN718 lists the expected ID for each catalog number.

Inverter Base ID: Control board installed on power base without current feedback

What it means: The 18H vector control board is fitted to a power base that has no output phase current sensors.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Power base with no output phase current sensors being used

First checks, in this order

1. Replace the power base with one that has output leg current feedback. Contact Baldor.

Logic Supply FLT: Logic power supply not working properly

What it means: The logic power supply inside the control is not working properly.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Power supply malfunction

First checks, in this order

1. Baldor's corrective action is to replace the logic power supply. Remove power and wait at least 5 minutes before opening the cover.

Lost User Data: Battery backed RAM parameters have been lost or corrupted

What it means: The parameters held in battery backed memory were lost or corrupted. When the fault is cleared (Reset), the control resets to factory preset values.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: after RESET the control returns to factory preset values

Likely causes

• Battery backed memory failure

First checks, in this order

1. Disconnect power to the control and apply power again (cycle power).
2. Enter all parameters again, for example from the User Settings recorded at the end of the manual.
3. Cycle power. If the problem persists, contact Baldor.

Low INIT Bus V: Insufficient bus voltage on start-up

What it means: When power was applied, the DC bus did not charge to a high enough voltage.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Improper AC line voltage

First checks, in this order

1. Disconnect the dynamic brake hardware and retry.
2. Check the input AC voltage level, for example 180 to 264 VAC 3 phase 60 Hz on 230 VAC models and 340 to 528 VAC 3 phase 60 Hz on 460 VAC models (MN718 specifications).

Memory Error: EEPROM error occurred

What it means: The control's EEPROM memory reported an error.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• EEPROM memory fault

First checks, in this order

1. Press RESET on the keypad.
2. If the fault remains, call Baldor.

New Base ID: Control board was changed since last operation

What it means: The control board found itself on a different power base than at the last power up, typically after a board change, and its parameters are not yet set up for it.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Software parameters not initialized on a newly installed control board

First checks, in this order

1. Press RESET on the keypad to clear the fault.
2. Cycle power (turn power off, then on).
3. Reset the parameter values to factory settings.
4. Open Diagnostic Info and compare the power base ID with Table 5-3 of MN718 to make sure they match.
5. Re-enter the parameter block values recorded in the User Settings at the end of the manual.
6. Autotune the control.

No EXB Installed: Programmed operating mode requires an expansion board

What it means: The operating mode set in the control needs an expansion board that is not installed.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Incorrect operating mode programmed
• Expansion board needed for the selected mode is not installed

First checks, in this order

1. Change the Operating Mode in the Level 1 Input block to one that does not require an expansion board.
2. Or install the correct expansion board for the selected operating mode.
3. Diagnostic Info shows which Group 1 or Group 2 expansion boards are installed.

Over Current FLT: Instantaneous over current condition detected by bus current sensor

What it means: The bus current sensor saw an instant current spike above the trip level.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Current Limit parameter set lower than the drive rating
• ACCEL or DECEL time too short
• Excessive load
• Encoder coupling slipping, broken or misaligned, or encoder bearing failure
• Excessive noise on the encoder lines
• Electrical noise from external DC or AC relay coils

First checks, in this order

1. Increase the PK Current Limit parameter in the Level 2 Output Limits block (MN723 adds: not above the drive rating).
2. Increase the ACCEL and DECEL parameters in the Level 1 ACCEL/DECEL Rate block.
3. Reduce the motor load and verify the control and motor sizing.
4. Correct or replace the encoder to motor coupling; replace the encoder if its bearing has failed.
5. Check the position counter in Diagnostic Information for jittering, check the encoder connections and route encoder leads away from power wiring.
6. Install reverse biased diodes across external DC relay coils and RC snubbers on external AC coils.

Overload - 1 min: Output current exceeded 1 minute rating

What it means: Output current stayed above the 1 minute overload rating for too long. MN718 rates overload capacity at 150% for 60 seconds in Constant Torque mode and 115% for 60 seconds in Variable Torque mode.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message). Its troubleshooting table prints Overload - 1 Min FLT.

Drive response: with Overload set to Fault the control trips and must be reset; with Foldback it reduces output current instead

Likely causes

• Peak output current above the 1 minute rating
• Motor overloaded
• ACCEL or DECEL times too short
• Encoder coupling slipping, broken or misaligned, or encoder bearing failure

First checks, in this order

1. Check the PK Current Limit parameter in the Level 2 Output Limits block.
2. If continuous running is wanted, change the Overload parameter in the Level 2 Protection block from Trip (Fault) to Foldback, which reduces output current instead of tripping.
3. Check the motor for overloading, increase the ACCEL and DECEL times and reduce the load.
4. Verify the control and motor are sized correctly.
5. Correct or replace the encoder coupling, and replace the encoder if its bearing has failed.

Overload - 3 sec: Output current exceeded 3 second rating

What it means: Output current went above the short time peak rating. MN718 rates it at 170 to 200% for 3 seconds in Constant Torque mode.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message). Its troubleshooting table prints Overload - 3 Sec FLT.

Drive response: with Overload set to Fault the control trips and must be reset; with Foldback it reduces output current instead

Likely causes

• Peak output current above the 3 second rating
• Motor overloaded
• ACCEL time too short
• Encoder coupling slipping, broken or misaligned, or encoder bearing failure

First checks, in this order

1. Check the PK Current Limit parameter in the Level 2 Output Limits block.
2. If continuous running is wanted, change the Overload parameter in the Level 2 Protection block from Trip (Fault) to Foldback.
3. Check the motor for overloading, increase the ACCEL time and reduce the load.
4. Verify the control and motor are sized correctly.
5. Correct or replace the encoder coupling, and replace the encoder if its bearing has failed.

Over speed: Motor RPM exceeded 110% of programmed MAX Motor Speed

What it means: Measured motor speed went above 110% of the maximum speed programmed in the control.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Motor speed above 110% of the programmed maximum
• Speed PROP Gain too low to hold speed (Baldor's corrective action raises it)

First checks, in this order

1. Check Max Output Speed in the Level 2 Output Limits block.
2. Increase Speed PROP Gain in the Level 1 Vector Control block.

µP Reset: Power applied before the Bus voltage reached 0VDC

What it means: Power was switched back on before the DC bus had fully discharged to 0 V. On the 18H this message is about power cycling, not a processor watchdog (compare the 15H row).^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Power was cycled before the bus voltage reached 0 VDC

First checks, in this order

1. Press RESET on the keypad.
2. Disconnect power and allow at least 5 minutes for the bus capacitors to discharge before applying power again.
3. If the fault remains, call Baldor.

PWR Base FLT: Desaturation of power device occurred or bus current threshold exceeded

What it means: An output power device came out of saturation or the bus current went over its threshold, which points to very high current or a grounding problem.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Improper ground
• Excessive current or excessive load
• Excessive power in the dynamic brake circuit
• Encoder coupling slipping, broken or misaligned, or encoder bearing failure
• Excessive noise on the encoder lines
• Electrical noise from external DC or AC relay coils

First checks, in this order

1. Make sure the control has a separate ground wire to earth ground; panel grounding or conduit connections are not sufficient.
2. Disconnect the motor leads from the control and retry. If the fault remains, call Baldor.
3. Correct the motor load and verify the control and motor sizing.
4. Verify the Ohm and Watt parameters of DC injection braking, increase the decel time and add optional dynamic braking hardware.
5. Check the encoder coupling, bearing and wiring; separate encoder leads from power wiring.
6. Install reverse biased diodes across external DC relay coils and RC snubbers on external AC coils.

Regen R PWR FLT: Regen power exceeded Dynamic Brake value (Level 2 Brake Adjust resistor rating)

What it means: The braking energy sent to the dynamic brake resistor is more than the resistor rating set in the Level 2 Brake Adjust block.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Incorrect dynamic brake parameter
• Regen power exceeded the dynamic brake resistor rating
• Input voltage too high

First checks, in this order

1. Check the Resistor Ohms and Resistor Watts parameters in the Level 2 Brake Adjust block.
2. Add optional dynamic braking hardware.
3. Verify the AC line voltage. Use a step down transformer if needed and a line reactor to minimize spikes.

Resolver Loss: Resolver feedback problem is indicated (if resolver used)

What it means: The control lost a valid resolver feedback signal (only when a resolver is used).^[3]

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Defective resolver
• Resolver power supply loss
• Defective wiring

First checks, in this order

1. Check the resolver to motor coupling; align or replace it if needed.
2. Verify the wiring, using the Resolver to Digital expansion board manual.
3. Electrically isolate the resolver from the motor.

Torque Prove FLT: Unbalanced current between all 3 motor phases

What it means: The output current in the three motor phases is not balanced. The check runs when Torque Proving is ON in the Level 2 Protection block.^[3]

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Unbalanced current in the 3 motor phases

First checks, in this order

1. Check continuity from the control to the motor windings and verify the motor connections.

User Fault Text: Custom software operating fault occurred

What it means: A fault defined by custom software loaded in the control has occurred.^[3][4]

Also on: 23H AC servo control (MN723 lists the same message)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Fault detected by custom software

First checks, in this order

1. Refer to the custom software fault list.

Unknown Fault: Fault occurred but cleared before its source could be identified

What it means: A fault happened but cleared before the control could tell what caused it.^[3][4]

Also on: 23H AC servo control (MN723 troubleshooting table, same indication)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Short lived fault, for example from high frequency noise on the AC line

First checks, in this order

1. Check the AC line for high frequency noise.
2. Check input switch connections and switching noise (added in the 23H manual).

Power Module: Power supply failure

What it means: A power supply failure was detected.^[3][4]

Also on: 23H AC servo control (MN723 troubleshooting table, same indication)

Drive response: motor operation stops and the message shows on the keypad; fix the cause, then press RESET

Likely causes

• Power supply failure

First checks, in this order

1. Press RESET on the keypad.
2. If the fault remains, call Baldor.