I am looking for a  3 phase 100 amp Normally Close mechanical contactor as a fail safe brake for a water turbine. I am trying to find a 3 phase mechanical contactor with the main contacts normally closed. I use that as the final safety brake to connect the PM generator with a resistor bank to prevent the turbine going over speed. All the motor mechanical contactors I seen are Normally Open, and I have a hard time finding a contactor that is 3 phase 460 volt and can handle 100A. Anyone have seen that some where?

Try looking on NHP there should have what you require

Peter, I Googled NHP and it come up to be Natural Health Product and other non-related stuff for the first 10 pages. Do you have a link to the company web site? or the full name of the company? Many thanks.

sorry no web site but email at pbeverid@aol.com

Simon Kearney

General Manager at NHP Electrical Engineering Products Pty Ltd
try thisv site

Can I suggest a different approach? U can use circuit breaker, like AZ-C100/3 and add release mechanism (like, AZ-XAA). So basically it's normaly close device, but in case of failure you can open it.
Much cheaper than NC contactor. The only disadvantage: in case of trip, you should manually turn it on.

Evgeny,

We cannot use you suggestion - it has to be Normally Close. We have a electronic solution before but that will not pass the customer's regulation.

Pete,

Two of my engineer has search most of the suppliers - ABB, Allen Bradly, Rockwell, Rockwell Automation, Mitsubishi Electric, Hitachi. They have spend over a week talking to their technical support, and come up with nothing. I am hoping someone here who has used such a device or have seen it recently, who is kind enough to let us know where they are.

Thank you.

get in touch with Siemens they make everything if not, let me know and i will contact some people in the mining industry

ok need to know , coil voltage, type of motor all information about use of contactor , do you need overload for contactor, really need all information, plus they do make one but cant remember where i saw it you could always try getting one specially made but it will cost heaps

The coil voltage is 110 Volt AC 60 Hz. The main contact are 3 phase 460 volt 100 Amps. The motor / generator is 16 pole 450 RPM @ 60 Hz, 3 phase 460 Volt 100 amps. The phase to neutral resistance is 0.018 ohm, Inductance Ld = Lq = 2.0 mH. Efficiency of using as a motor is 97.4%; efficiency using as generator is 97.7%. Over load capability is 150% for 30 minutes. Insulation rated at 180 degree C, with VFD setting to trip at 130 degree C.

We designed and built these motors a couple years ago. Is efficiency of is not as good as our new design; but we have quite a number of them out in the field. So we still have to service them. We have been looking for the mechanical contact for quite a while to replace the Solid State Relay solution we are using. We just don't have the luck finding them - even our two engineers have worked in the motor and control field for 30 years. They all have seen and used them before, but was not able to find them again.

Really appreciate someone here who just happen to know where they are. Thanks.