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  2. Event Code Help (F0 - F65)

F3 Code Help – Braking Resistor or Low Bus Voltage (Product Model Dependent)

F3 (MSM or CX models): Braking Resistor On Too Long F3 (MMX/MMV or Ultra models): Low Bus Voltage

Code Meaning (MSM or CX models): The braking resistor has been on too long.

Further Information/Troubleshooting Tips:

  1. The resistance of the external resistor may be too large. The resistance is considered too large if it more than 110% of the value determined by PE® (especially applicable if you not using the recommended PE® resistor bank). If this is the case, replace the resistor with one that agrees with the specification. Never use a resistor that has fewer ohms than the specification requires!
  2. The line voltage is too high. Make sure that the incoming line voltage is within specifications.
  3. A transistor may be shorted in the drive. To check this, detach the motor and run the drive at some speed. While running, check the DC voltage across the open resistor (CAUTION: As much as 800 volts may be present!) If the transistor is working properly, there should only be a few volts present at most. If not, return the drive to the factory for repair.
  4. On a hoist, this trip may indicate that the load brake is slipping excessively or that it has failed completely. Examine the load brake and make any adjustments or repairs as necessary.

(MMX or MMV™ models): Low Bus Voltage

Code Meaning: The voltage across the main buss capacitors has dropped below a preset level while the drive is running. This could indicate fluctuating input power, or it could mean your power is cutting off temporarily for some reason (power-cut off upper limit switches, a bad/worn spot on your powered rails or electrification, etc).

Further Information/Troubleshooting Tips:

If you are seeing this trip, it might be beneficial to measure or record the line power coming in, since fluctuating line power is usually the cause. If voltage fluctuation is happening too quickly to measure with a standard DMM, a recording meter may be necessary. By default, you will only see this trip if the line power drops below approximately 80% of the expected line power for an extended length of time.