Temperature Limit Switch Failure
Temperature Limit Switch Failure
(OP)
Hi all,
We had a temperature limit switch failure problem in a heat exchange fan control circuit. The fan is a 1/6 HP single phase motor, and it is controlled by a Honeywell 'BM-2R-A2' temperature limit switch. This limit switch is rated for 1/2 HP that shouldn't have any problem in a 1/6 HP case, but it kept failing and the contactor got welded. Does anyone have some insight regarding this? Would you think that adding a surge suppressor would help?
Thanks,
JS
We had a temperature limit switch failure problem in a heat exchange fan control circuit. The fan is a 1/6 HP single phase motor, and it is controlled by a Honeywell 'BM-2R-A2' temperature limit switch. This limit switch is rated for 1/2 HP that shouldn't have any problem in a 1/6 HP case, but it kept failing and the contactor got welded. Does anyone have some insight regarding this? Would you think that adding a surge suppressor would help?
Thanks,
JS





RE: Temperature Limit Switch Failure
Obviously, you could use it as such with added hardware, and that may be the case. Is the switch rated for temperatures
in your application?
RE: Temperature Limit Switch Failure
Thanks a lot for replying. You can find all the spec via: http://sensing.honeywell.com/honeywell-sensing-mic... and http://sensing.honeywell.com/nomenclature-micro-sw...
The operating range is : -55 °C to 85 °C [-67 °F to 185 °F], and that is sufficient for our case (125 °F).
RE: Temperature Limit Switch Failure
NOTE: There is no correlation between current rating and HP ratings of switches.
Is there a possibility that the electrical damage is precipitated by mechanical damage due to possible over travel of the operating mechanism?
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Temperature Limit Switch Failure
Bill, if you look at this tech spec: https://stevenengineering.com/tech_support/PDFs/31.... It says that it is HP rated. Once the contacts close, the moving contact stops, and the over-travel shouldn't have further impacts. Am I understanding it right?
RE: Temperature Limit Switch Failure
Water or condensation getting to the switch?
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This is normally the space where people post something insightful.
RE: Temperature Limit Switch Failure
Keith Cress
kcress - http://www.flaminsystems.com
RE: Temperature Limit Switch Failure
RE: Temperature Limit Switch Failure
Are you trying to limit temperature or what? Sorry, I dont understand. I see only a micro switch
lukin1977
RE: Temperature Limit Switch Failure
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Temperature Limit Switch Failure
We also measured the load current. It runs at ~4.5A, with a ~11A inrush on startup.