vfd over voltage code

[hvac17011]

i have a 40ton vfd automation direct gs34040 vfd. it has been in for 4 years no issues. its a 480 drive. 486/482/482 input voltage. it went in alarm sunday. i looked at today. it alarmed out if it went to 35 hz. i changed accel times and a few other parameters. It is on a dessicant dehumidifier. it mostly runs at 60 ate 486hz 365 days a year unless there is a power blip. it now will ramp up but alarms on decel even though i increased decel times. i was on phone with tech support for hours. They are not sure. it faults on dc bus over voltage . why do i have to change settings after 4 years. the blower is a centrifugal type fan no belts. motor seems smooth amps good. the dc buss is 748 at 60 hz but i calculate it should be 687. when it decels the bus voltage goes down according to screen but still trips out. any ideas.

[jbhenergy]

Can’t remember if mine was dc under or over but it was on a 30 horse motor for a tower fan. Book indicated to Meg the motor which we did and found it to be on its way out.

Had another one that would blow one fuse of three. IR scan showed it was hot, and slightly higher amps then others. Motor checked out fine. Installed a line reactor and it took care of the situation.
Looked like a big transformer but all it really does is clean up the electric signal.


Sent from my iPhone using Tapatalk

[ehsx]

Line reactor is listed as an accessory. Do you have it?

Line reactor:
Increased reliability and life span of the VFD
Provide some protection against over-voltage trips
A cost-effective solution to reduce harmonic distortion
Provide some buffering against voltage spikes

[hvac17011]

no to reactor

[Paul Benkovitz]

The only time I ran into a DC buss over voltage was when a drive was trying to start an already spinning motor. That drive didn't have a catch option so I had it brake before starting. You can also get that error if the motor is spinning faster than the current drive speed. A building imbalance can cause that on fans.