Blowing fuses

[jpmreno]

Hey everybody I have a big problem and I cant figure it out. Can someone please help. I turn the key on control box and PID and Timer light up. But when I go to press the switch to start the oven it blows the 1 amp fuse. Any ideas what's happening I'm stumped.

 

[JayEff]

I know a thing or two about electricity, perhaps I can help, unless someone with more specific knowledge already knows the answer.

Unfortunately, I'm not entirely sure on your setup, despite the extensive diagram, and I'm not familiar with the abbreviation PID (or AWG for that matter) (..hobby low-voltage electrician here)

Usually, a fuse blows when more electricity flows than the device containing the fuse expects. This can happen if your consuming device has a short or a similar fault. What exactly is on the line whose fuse blows?

You say you "start the oven" - I'm not aware of any heating equipment that uses only one amp of power. a simple calculation with the 240V taken from the diagram says your oven has to be only (less than) 240 Watts of power which sounds like a heavy duty aquarium heater.

I, personally, need more context, sorry. I hope others can figure it out quickly for you, but if not, if you can give me context, I'll try my best!

 

[ajdelange]

There is only one thing downstream of the switch and that is the contactor coil. Assuming the contactor coil is designed to draw less than an amp. there must be a short in it or its wiring. Try disconnecting the coil at its terminals and then operate the switch. If the fuses do not blow then the coil is probably the culprit. Check its resistance with an ohm meter. If the fuses continue to blow it is the wiring.

 

[MaryB]

Illuminated pushbutton switch SW 1 may have a shorted bulb or it is just bad... or the contactor coil is burned out and shorted.

 

[doug293cz]

AJ's and Mary's suggestions are both good. Another possibility is that the wiring is mixed up on the SW1/SW16 terminals, such that when the switch is closed Line1 and Line2 are shorted together.

I found some specs on the coil used in the CN-PBC302-240V contactor.

• Nominal DC coil resistance: 1800 ohms
• Nominal coil in-rush power: 32 VA
• Nominal coil operating power: 6 VA

So when SW1/SW16 is initially turned on the contactor coil should draw 32 VA / 240 V = 0.13 A. So, if everything is wired correctly, and there are no defective components, the fuses shouldn't be blowing.

Brew on

 

[doug293cz]

I think I found the problem. OP sent me some pics of the inside of the box. Looks like the two wires coming out of SW1/SW16 are connected wrong on the contactor. They connect to two coil lugs that are shorted together (both wires connect to one side of the coil.) One wire needs to connect to a lug on one side of the contactor, and the other wire needs to connect to a lug on the other side of the contactor. The pic below shows the fix that needs to be made.



Brew on

 

[jpmreno]

Thanks everybody that was it.