Solution of SD700 over-voltage troubleshooting

Fault Name:

Over-voltage troubleshooting.

Fault Symptom:

Er.400 is reported on SD700 servo drive (the following sentences call it over-voltage).

Causes:

The output voltage of the main circuit is excessive and badly fluctuant.

Motor generation makes main circuit voltage increase.

The voltage detection circuit is damaged or the output voltage of the switching power supply is abnormal.

Analysis:

As we do the over-voltage trouble-shooting, it includes two situations as below:

The over-voltage is reported when the motor stops during unable time:

Check if the voltage from the input to the main circuit with a multimeter is greater than the specified, the over-voltage threshold of 220V models is DC400V and AC282V, the over-voltage threshold of 380V models is DC800V and AC565V. If the input voltage reaches the over-voltage threshold, please replace the input power immediately.

Voltage value of the main circuit is collected through the monitoring parameters Un140 or virtual oscilloscope channel, according to the read voltage value to determine the driver's main circuit voltage and the current value of the alarm voltage fluctuations are abnormal, if the read voltage value is abnormal or the fluctuation itself is abnormal, compare the test results of step a. If the voltage value read by the multimeter and the voltage value read by the driver are too different, the internal voltage detection circuit of the driver is damaged or the output voltage of the switching power supply is abnormal. Please return to the factory for repairing.

Fast and frequent acceleration and deceleration during operation. When the motor shaft ends with large inertia load in rapid acceleration and deceleration, the energy is fed back to the main circuit grid. If the regenerative resistor is not connected or is too small, the over-voltage faults will be reported.

Without regenerative resistor: Observe the main circuit voltage and feedback speed through the virtual oscilloscope channel. In the acceleration / deceleration section, the main circuit voltage rises steadily until the overvoltage is reported. Check whether the driver is connected to the regenerative resistor normally.

Connect to the regeneration resistor: parameter settings are not reasonable, please refer to the regeneration resistor settings instructions:
The regenerative resistor power should be set to a value that matches the allowable power of the connected external regenerative resistor. The setting differs depending on the cooling condition of the external regenerative resistor. When it’s in self-cooling method (natural convection cooling): Set to 20% or less of the regenerative resistor power (W). When it’s in forced air cooling: Set to 50% or less of the regenerative resistor power (W).

Example: When the power of the self-cooling external regenerative resistor is 100W, 100W × 20% = 20W, Pn012 is set to 2.
If the parameters are set correctly according to the instructions, the over-voltage is still reported or the regeneration overload is occasionally reported. That means the capacity of the selected regenerative resistor is too small to meet the requirements of the current operating conditions. You need to select a larger resistor again.

Note: 

The resistance value of the regenerative resistor must be selected to meet the minimum allowable resistance condition for each power section.