I have an older Hussmann protocol and have a defrost problem, the heaters are not working on one system.
I believe it is the breaker in the rack, does anyone know if this is a special breaker, which also is a switch built in.
Turning the defrost on and off through the breaker?
I am having a hard time getting a hold of Hussmann, seems my call is very important to them, but yet I still am on hold for hours.
I work on a couple of these units, the breaker is a motorized breaker that acts like a contactor... Kinda. I guess they do that to save space (just add more to the panelboard and not use big contactors with the wiring that takes up room).
Breaker receives signal from the rack controller (danfoss, Emerson, whatever), and closes..but it isn't instant like contactor it takes a few moments. I'd check the tightness of connections at the breakers too, these units tend to vibrate a little bit ❄
This is true for the ones I've worked on, each customer has specific needs and your system may vary.
Last edited by mr_guy; 08-31-2015 at 09:35 PM.
It was called Power Link. Go to section 4-21 for info:
Thank you to both of you, this helped a lot
Does the defrost relay contacts remain closed on the output board.
I have had a problem with a older Protocol with the PCS controller; it was just with one of five low temp circuits.
The system would call for a scheduled defrost or if you put system into defrost would hear the defrost relay click but the contacts
wouldn't close; the relay for the solenoid valve would open but the relay for defrost was intermittent and sometimes the contacts
wouldn't close; happened on two different Protocols. Only happened with PCS controller.
Was also told the Power Link was to save space rather than having a very large defrost heater contactor.