Phase loss protection relay

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Steve and Bob,
Thanks for the replies!

The ones that I will be installing will be on roof top package A/C units on top of a school. I don't want to make a lot of trips up to the roof for nuisance tripping.

SqD says the Time Mark #2664 and the SqD 8430 MPD are roughly equivalent. However the #2664 has an adjustable time delay in addition to having adjustable voltage settings.

It sounds like the Time Mark should work for the application.

Anyone else have any experience or opinion on this issue?
 
i have had no problems with the time mark units and are accurate to what you dial into them. i have also used the unit manufactured for a/c unit single phase protection called "lumberjack" -- they are not as accurate but are good enough to protect the average a/c unit. consider the equipment or function your trying to protect and then spend the proper amount of money. i used them mainly on variable speed drive systems and chiller controls. $200 isn't too much to spend protecting a 100 hp compressor motor!!!!!!!!!!
 
Charlie - Thanks for the reply, and the first-hand experience!

It's good to know that the Time Mark units work as advertised and are reliable!

I would think that all large 3 phase motor loads should have phase loss protection. Chillers would definitely qualify - it would be cheap insurance for them.
 
i used to use the "lumberjack" units --they were sold at the a/c mechanical supply house and had no adjustment. just were rated for line voltage ---480 or 208 etc.. i like the ability to adjust the trip set point to control neucensed trips if you find yourself in an area where the voltage is low like 460. sorry about the remark about chillers---what i meant was on support equipment for chillers............
 
Charlie - many thanks for the information you provided to me! I hope I can return the favor some time. :D

I've never seen one of the "lumberjack" units, but it sounds like the Time Mark ones would do a better job. That's what I'll recommend that we use.

Thanks again!!!

And thanks again to all that have responded! You guys are GREAT!!!
 
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