Resistance Boiler
Resistance Boiler
(OP)
Need help with a Brand New Resistance Boiler eating up contactors
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RE: Resistance Boiler
Voltages, currents, kW ratings, divisions of heating elements, quantity and type of contactors, what "eating up contactors" means in technical terms, how often, etc., etc. More information will always allow better responses.
RE: Resistance Boiler
Thanks for the reply, let me put something together for you to look at.
RE: Resistance Boiler
I have two brand new Precision Electric Boilers
Model # ST-30D-760D-480/150
PPh - 2593
KW - 760
Contactors are Furnas 42CF35AF - 480Volt = 40 Amp
Elements 38 @ 20 KW - 9 @ 80 & 1@ 40
Contactors 19
Just after three days of number 1 boiler being on line the contactors contacts are burning up.
I have been in touch with Precision and they say there's nothing is wrong with the boiler.
Voltag coming into the service disconnect is between 479-481
Thank you for your time
Wes
RE: Resistance Boiler
On the other hand, your smallest element appears to draw nearly 42A (I'm assuming a single-phase 480V element), and that might suggest a cause of your problems.
RE: Resistance Boiler
The other issue is adequate control power voltage to keep the contactors pulled in tightly. If your control power transformer is too small and is powering multiple contactors, a low control voltage could be the problem.
RE: Resistance Boiler
RE: Resistance Boiler
With the information so far, I agree with cbarn24050 as to the controller fast cycling.
respectfully
RE: Resistance Boiler
760 kW, okay 38 elements x 20 kW per element, that matches up. But: 9@80 and 1@40 - is this the amp draw, and of what, since 9+1 doesn't add to 38.
(760,000 Watts)/480 volts/19 contactors = 83+ amps per contactor. But the contactors are only rated for 40 amps?
Something don't add up.
RE: Resistance Boiler
You need to use a factor of sqrt.3, but it's still a little over the top even before adding the oddball elements.
(48 Amps)
respectfully
RE: Resistance Boiler
RE: Resistance Boiler
RE: Resistance Boiler
The boilers stay on line and are not starting up cold.
The average amperage draw is 43 Amps per leg 3 Phase
The contactors do sequence as per load demand
RE: Resistance Boiler
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Sometimes I only open my mouth to swap feet...
RE: Resistance Boiler
RE: Resistance Boiler
RE: Resistance Boiler
RE: Resistance Boiler
respectfully
RE: Resistance Boiler
Don
RE: Resistance Boiler
What were its ratings?
Why did the boiler manufacturer allow you to connect to a controller with marginal ratings?
TTFN