Trouble On Variable Frequency Driver

Usually this is caused by the load actually "pulling" the motor, which over drives it and turns it into a generator, then the energy gets to the DC bus and has nowhere to go. This will happen on some blower applications where you have decel enabled and a long column of air moving. Your control system is calling for a slower speed from the blower, the drive responds immediately, but the air column continues to keep moving at the higher speed and causes a motor speed that is higher than the VFD commanded speed. If you want to test this theory, disable the Decel, change it to "coast to stop". If the problem goes away, that's what it was. What you decide to do from there will likely involve discussions with the air handling people too.

You have already received some good information but I'll add info from the manual.

Shawn

A07400 (N) Drive: DC link voltage maximum controller active

Reaction:

NONE

Acknowledge:

NONE

Cause:

The DC link voltage controller has been activated because the upper switch-in threshold has been exceeded (r1242,

r1282).

The ramp-down times are automatically increased in order to maintain the DC link voltage (r0070) within the permissible

limits. There is a system deviation between the setpoint and actual speeds.

When the DC link voltage controller is switched out (disabled), this is the reason that the ramp-function generator

output is set to the speed actual value.

See also: p1240 (Vdc controller or Vdc monitoring configuration (vector control)), p1280 (Vdc controller or Vdc monitoring

configuration (V/f))

Remedy:

If the controller is not to intervene:

- increase the ramp-down times.

- shut down the Vdc_max controller (p1280 = 0).

If the ramp-down times are not to be changed:

- use a chopper or regenerative feedback unit.

F30002 Power unit: DC link voltage, overvoltage

Reaction:

OFF2

Acknowledge:

IMMEDIATELY

Cause:

The power unit has detected an overvoltage condition in the DC link.

- motor regenerates too much energy.

- line supply voltage too high.

- line phase interrupted.

- DC-link voltage control switched off.

- dynamic response of DC-link voltage controller excessive or insufficient.

Fault value (r0949, interpret decimal):

DC link voltage [1 bit = 100 mV].

Remedy:

-increase the ramp-down time (p1121).

- set the rounding times (p1130, p1136). This is particularly recommended in V/f operation to relieve the DC link voltage

controller with rapid ramp-down times of the ramp-function generator.

- Activate the DC link voltage controller (p1240, p1280).

- adapt the dynamic response of the DC-link voltage controller (p1243, p1247, p1283, p1287).

- Check the line connection voltage (p0210).

- check and correct the phase assignment at the power unit.

- check the line supply phases.

See also: p0210 (Drive unit line supply voltage), p1240 (Vdc controller or Vdc monitoring configuration (vector control))