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STH-10 Overload Question

Posted: Wed Dec 09, 2015 2:54 am
by theroofable
Hello,

You may remember my thread about the STH-10A restoration and installation I did a few months back. https://airraidsirens.com/forums/viewto ... =2&t=15919. Well now the electrician has finally gotten around to doing the final hookup. One thing we still need to figure out is the overloads. Per the manual, it says to bring the two overload lines (P1 and P2) back to the motor starter and make the connections there. With the federal RC5 contactor it has the proper terminals where you connect the overload lines.

So the contactor I am using is just a standard automation direct GH15GT contactor with a properly sized overload for 40Amps. My question, where would the P1 and P2 lines hook up when using this equipment? Is it even necessary to hook up the P1 and P2 lines coming from the siren when there is already an overload on the contactor?

For the technical contactor available connections are L1 L2 L3, T1 T2 T3, coil A1 A2, and then the normally closed (95 and 96), and normally open (97 and 98).

Thanks for the help. Rough work for the wiring should be done this week, and should be running by the weekend. Ill put a video on the original thread when all is complete.

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Re: STH-10 Overload Question

Posted: Wed Dec 09, 2015 3:58 am
by Andys Live WX
Those two wires are each end of the thermal cut out inside the motor. I will try to help you with my knowledge of motor controls. I think you put P1 to your holding contact #2 and P2 with your incoming signal control power so then if your thermal cut out opens, no voltage can flow to the coil. So essentially the control power has to go through the thermal cut out and makes its way to holding contact #2 (#97), and when the contacts are closed it goes to #3 (#98) and then straight to the coil. #95 and #96 would not be used.

Re: STH-10 Overload Question

Posted: Fri Dec 11, 2015 12:04 am
by theroofable
Thanks for the info, that clears it up a bit. Rough work was done today, final connections will be tomorrow.