Max ocpd for abb vfd
- Thread starter darekelec
- Start date
ptonsparky
Tom
- Occupation
- EC - retired
Read the fine manual.
Eta: You may need to be using fuses. The breaker could stay but fusing or other protective device will need to be installed. RTFM
Last edited:
ptonsparky
Tom
- Occupation
- EC - retired
You have the condensed version.
Welcome to the world of VFDs.
Somewhere in the first few pages it states that you must read the entire book or words to that affect. CYA or not, it is where you need to begin.
Eddie702
Licensed Electrician
- Location
- Western Massachusetts
- Occupation
- Electrician
You need to follow the MFG. instructions. They may want fuses or a CB. Every drive and every mfg is different. Its not one size fits all.
ptonsparky
Tom
- Occupation
- EC - retired
You could try a 100.
80 might work.
Heck, a 50 may. What will the VFD be operating at?
80 might work.
Heck, a 50 may. What will the VFD be operating at?
ptonsparky
Tom
- Occupation
- EC - retired
Will it be operating at full load most of the time, or practically never?
Code requires 125% of its, the VFD, rating for the conductors to it. Will the 100 amp breaker work? Most likely.
Read the fine manual because you may need specified protection ahead of it somewhere.
ptonsparky
Tom
- Occupation
- EC - retired
Ah, the table tells you the max model of breaker to use.
Do you have that model of breaker in a 100 amp size?
Yes, use it. It can’t more than shut down.
Do you have that model of breaker in a 100 amp size?
Yes, use it. It can’t more than shut down.
You can keep the 200 amp circuit breaker if you install a fused safety switch or and
You could keep the 200 amp circuit breaker as long as you install a fused safety switch or a circuit breaker . Going by the ABB chart it should be a 150 amp circuit breaker. I'm old school and for over 90% of the motors that I wired up over 50 years liked to only go 125% over nameplate Amps who!e using quality 200 KIAC rated time delay fuses. On numerous drives without bypasses this 125% thinking never failed as on all the drives that I installed or worked on had at least a ten second ramp up time greatly reducing inrush current. On centrifuges that took over 20 seconds to reach full speed & air compressors & refrigerant compressors had to usually go with 175% of motor FLA. For a drive rated for 88 amps output and no bypass I would use 110 amp time delay fuses.I have installed VFD'S for 40 to 125 HP fans using the 125% sizing with no problem. I always ordered drives with built in disconnect switch and input fuses.
ptonsparky
Tom
- Occupation
- EC - retired
FWIW, I have a 1Ph in 3Ph out VFD that's rated 27.8 amps input VT. Home well.
ChBr 2 pole 20 amp breaker, no fusing, #12 thwn. Is it right? Nope. Am I worried about rapid disassembly? Nope. Warranty? Been that way for 14 years, so No.
ChBr 2 pole 20 amp breaker, no fusing, #12 thwn. Is it right? Nope. Am I worried about rapid disassembly? Nope. Warranty? Been that way for 14 years, so No.
ptonsparky
Tom
- Occupation
- EC - retired
I've never had to do a bypass, but I would wire that up just as if it were a standard ATL starter.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
30HP 230V, NEC table says 80A, 430.52 says CB is max. 250%, 80 x 2.5 = 200A. Good to go for the bypass...
So now your only problem is that the VFD cannot have a 200A breaker ahead of it. So what you do is put 150A FUSES downstream of the breaker, but ONLY ahead of the VFD.