Undervoltage Relay

OkiePC · Aug 26, 2005

Hi All!
I have a failing undervoltage relay protecting a 200HP rubber mill. It has a 460vac coil, a N.C. contact and a N.O. contact. GE finally found info for me after two days of searching in a printed copy of a 1972 catalog. It is factory set to drop out at 70% voltage rating and pick up at 90%. The big surprise was the fact that they can still get me an exact replacement...for $1172. I've never had to update one of these before, but I'm sure there's something better and cheaper on the market. By the way, the control voltage (going through the contacts) is 230vac. Any recommendations what I should replace it with?

Thanks
Paul C.

leitmotif · Aug 26, 2005

I got one from Grainger several years ago.
Solid state , single phase, with integral 60 amp CT, SPDT output switch for about $50 to 75. All single unit encapsulated, worked well. See if They have large unit for your need.

Dan Bentler

JvdV · Aug 26, 2005

There would also be the option of an Voltage sensing unit and a big contactor.
The contactor would switch the main current to the unit you want to protect.
The voltage sensing unit would be in the coil side of the contactor.
The voltage sensing unit can be set for dropping at 20-100% of the rated voltage. Also the switching on level can be set at a specific voltage. Time delay and hysteresis are also adjustable.

I think it would be a mutch cheaper solution than $1172,=
I can give you some documentaion on the volting sensing units. We use them for switching generators on and of for emergancy power supply in hospitals, etc.

Regards,
Jurgen

OkiePC · Aug 26, 2005

The relay ($1172 model) contacts are in the control voltage circuit and do not switch more than 0.5 amps at 230vac. I'm looking at voltage monitoring relays now, and there are hundreds of choices. The original lasted 25 years. I hope I can find something as dependable. Most of those I've checked only have a single form c contact. I need a N.C. and a N.O. contact that are isolated from each other to avoid modifying the control circuit.

JvdV · Aug 26, 2005

The ones we use are from crompton and SEG. Both are very relayable.

Regards,
Jurgen

Mickey · Aug 26, 2005

Have a look here

http://www.globalspec.com/supplier/Catalog/TimeMark#anchor25

TRACY H · Aug 26, 2005

Another look

Here
http://www.time-mark.com/products.php?viewapps=1

Tark · Aug 26, 2005

This is what I like to use -

http://www.symcominc.com/catalog/3_phase_vm/250A.html

They make quite a few different models, but this one is good for voltage ranges from 190 - 480VAC, so I can use the same model for 240 or 480.

To be honest I have switched from using Time Mark to using SymCom. We were having lots of problems with the Time Marks, esp during lightning storms. In the 7 years since we've switched to the SymCom, I've had to replace only one.

OkiePC · Aug 26, 2005

Tark! That model looks like exactly what I need. After I double check all the numbers, I think I'll give it a try.

Thanks to all for your input...

twbtxnca · Aug 26, 2005

Here are some from ABB
http://www.ssac.com/standard/ff-railmnt.htm
REGARDS,
Tom

BoxerBrats · Aug 26, 2005

I dont know if yhis feasable to meet your needs, On one projct I worked on we put in a 3 phase voltage transducer, with a 4-20 ma signal to AD plc, then programmed if a voltage drop, it will shut the pump down, and send out a alarm

The voltage transduce was only around $250, and the AD plc brick was only $100, and another 4200 for the analog card

was actually a cheap procedure, since weneed the plc to control the flow anyway, was a easy solution

Undervoltage Relay

OkiePC

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