not my design but, customer wants to move a blender with 20hp motor that’s wired 480v to a new location that has a 225 and 208/120 service…. I though the easiest solution was a pump panel from square d. I know a nema 3 starter says it’s good to run a 25hp at 200 volts, but everything else that is listed in specs from square d only gives voltages of 240and 480. I was thinking something like this. With 100 amp fuses. What do you guys think, have any suggestions?
Pump panel for a 25hp on 208/120 system
- Thread starter Necnerd
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ptonsparky
Tom
- Occupation
- EC - retired
100 amp fuses are pushing your luck. Depends on what your load is like. 125 or 150 might be better
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Is it a dual-voltage motor?
That’s also something I was wondering, I didn’t know if all motors were rated to run on 208 volts… I’m not exactly sure . It’s above an open blender for wet fertilizer snd it’s totally corroded… I’m trying to talk them into getting a new motor as well since this one has no nameplate all I can tell is it’s a baldor.… I’m guessing it’s a 25 hp because of its size, the breaker size and the over load settings….
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Opening the wiring compartment may tell you whether it's convertible.
A starter or pump panel cannot change the voltage, but a VFD might.
A starter or pump panel cannot change the voltage, but a VFD might.
ptonsparky
Tom
- Occupation
- EC - retired
If you're really worried about the 208 volts a couple buck/boost transformers would get you where you need to be for relatively low cost. Cheap even.
Eddie702
Licensed Electrician
- Location
- Western Massachusetts
- Occupation
- Electrician
Most Baldors (not that I ever agreed with this) are rated 208/240/480. Ihave also noticed in some cases if they are on 240 they run pretty hot
430.52 states I can go up to 250% of flc in 430.245 for inverse time breaker and 175% for fuses. flc should be 74.8 if this is in fact a 25 hp. I had a schnieder electric slip stick i was going off of and they say 100a for fuse and mcp size...
ptonsparky
Tom
- Occupation
- EC - retired
A 208 25HP motor is rated at 74.8 amps. 1,25* 74.8 = 93.5 That is putting it very close to minimum fusing for overload protection.
68* 1.25 = 85 for a 230 V motor. A bit more leeway.
68* 1.25 = 85 for a 230 V motor. A bit more leeway.
the peckerhead cover is taped and silicone on, it was cold yesterday so i didnt even bother. ill have to see what i can find out but im guessing all the info is corroded away... yeah I dont think they are wanting to spend any money or time on this... they thought they could just swap them.... which doesn't work. I think the best idea is to tell them they need a new motor since i cant find any info on the existing to size it or set ol, ect. i guess i just need to find a way to control the new motor and the pump panel was what i thought of first.... im just not sure that its rated for 208volt application.
gotcha, that makes sense, i just when off the old slip stick to get an idea of what was needed. what I'm most concerned about is finding a pump panel that will work on 208volts and run a 20 or 25 hp motor... after looking at the bucket that the motor was hooked up id say its actually a 20hp. breaker is a 60A and the overloads were set on 27amps... so if i take that motor from 480 to 208 volts i should get 59.4x1.25=74.3
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
I am not sure why, but for some reason it seems to me that the slide rule type calculators always ended up giving you what was the minimum practical value for OCPD rating based on motor size and available fuse or MCCB ratings available.
Why obsess over using a pump panel. Just get a combination starter. Probably cost less and would appear to be quite adequate for what you are doing.
You could even make something up yourself.
Why obsess over using a pump panel. Just get a combination starter. Probably cost less and would appear to be quite adequate for what you are doing.
You could even make something up yourself.
ptonsparky
Tom
- Occupation
- EC - retired
A PP is available in my neck of the woods. A combination starter was special order even BC.
Yeah I agree, I usually always sit down and try to do actual calculations, but there handy for in the field… that was my next choice, that’s what is there now, but it’s too small… this is what I was looking at…
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That’s what I was thinking pump panel, also the pp can go outside by motor and be used to disconnect with in site. Breaker for contractor is inside building not within site…
So 409 doesnt apply? I could legally buy a size three starter and the correct overload and install it in an enclosure, and this would not be considered and industrial control panel because i only have the contactor and overload inside that enclosure, which would only be one component.
74.8x1.75 is 130.9 so i think 125 is the largest i can go if the motor is indeed a 25hp...
Here is the design I came up with for a 20hp motor. the top one is a added motor starter in the control room. Goes from 125a cb to the line side of contractor with #4 copper. I’d then go outside to a non fused disconnect suitable for 20hp at 208volt. From the load side of disconnect I planned on running #4type w so…. Pump panel design is same thing Essentially. Goes from 125a cb inside panel control room. Goes outside to pump panel woth 4 copper. I would have to get control wires from push buttons inside control room outside to pump panel and then run 4 type a up to the motor from the load side of pump pane contractor…
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Disregard this calulation ptonsparky i looked at that wrong. I can go up to the next size fuse of 150amps, I also believe if the motor didnt start i could use the exception 2 and increase to 225% of the flc... I think what you were saying is that the panel presented has a max circuit breaker ct rating of 100, so if i have to go up to a bigger fuse than ill also need to go up to a bigger panel?
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