200Hp motor starter

[Ambient44]

I have a 200hp motor on a pump at 600' from the source. the voltage drop calculates to be around 2.6% depending on the ambient temperature. which would give me 466.6volts at the motor. The pump manufacturer is saying they will not recomend a starter at the source with controls at the motor due to liability issues with the motor, they only will sell a soft start in an explosion proof enclosure to be installed at the motor with all controls incorporated into the enclosure. It is an Class 1 division II atmosphere and would need an explosion proof enclosure which makes the price increadibly high. My initial reaction is that they are only trying to sell the more expensive starter.
Has anyone heard of a reason why there would be a liability issue on a soft start being installed at the source with controls ran to the pump location?

Thanks,
Tom

 

[iwire]

In most cases, unless you meet one of the exceptions (and it sounds like you might) the NEC requires a disconnecting means at the motor not just controls.

 

[don_resqcapt19]

I see no reason why there would be a problem with the motor controller remote from the controlled motor. That is a very common installation.
I have a 200 hp motor on a VFD that is about 2000 feet from the drive.

 

[Jraef]

I think your assessment might be correct, but there may be another reason (see below). There is no reason why a soft starter needs to be close to the motor. I have had runs in excess of 1000', never a problem. I ALWAYS recommend to people using soft starters and VFDs that they locate them outside of the hazardous area, the cost is way to high to deal with the heat they create in the enclosure. Putting a local Ex Proof disconnect within sight of the motor is a LOT less expensive.

NEMA motors are designed around 460V for a 480V supply precisely for this reason. If they are telling you otherwise I think they are covering something up. For example they may be using an IEC motor that is rated for 400V 50Hz. When you supply that with 60Hz, the V/Hz ratio must remain the same and if you use the 8:1 ratio, that means 480V at 60Hz. IEC motors also do not have a "Service Factor" that allows for out-of-tolerance voltage supply, so if you give it 466.6V normally and the supply drops even further within the utility tolerance, the combined VD may be too much for it.

There could also be other similar issues, i.e. VD problems with the control circuit because some soft starters use 24VDC control and if you run out to the local control box and back to the soft starter 1200', it may not work right.

Bottom line though, if they are unwavering in that their warranty will be nullified if you don't do it their way, you may have no choice.

 

[weressl]

I have a 200hp motor on a pump at 600' from the source. the voltage drop calculates to be around 2.6% depending on the ambient temperature. which would give me 466.6volts at the motor. The pump manufacturer is saying they will not recomend a starter at the source with controls at the motor due to liability issues with the motor, they only will sell a soft start in an explosion proof enclosure to be installed at the motor with all controls incorporated into the enclosure. It is an Class 1 division II atmosphere and would need an explosion proof enclosure which makes the price increadibly high. My initial reaction is that they are only trying to sell the more expensive starter.
Has anyone heard of a reason why there would be a liability issue on a soft start being installed at the source with controls ran to the pump location?

Thanks,
Tom

I would ask for a clear, documented technical explanation, bolstered by Code and ASNI standard references. I would NOT buy a starter that is application restrictive. Is the starter listed and labeled for US use? Standard ANSI equipment - motor, cable and starter - installed according to the NEC should have no issues with this distance and voltage drop.

Local disconnect is NOT necessarily required under some circumstances.

If, for whatever reason, I decide that I need to install a local ASD or SSRV with a local disconnect I would investigate the Class Z purged enclosure option in Class I, Div. 2 location.