I'm working on a 3 phase 240v motore starter with a 240v coil for the city fire sirens. I have one side of the coil fed with a 120v leg from C phase and the other side is switched off of B phase. I have 120v to ground on each leg but 0v in between. I tested the coil and I am reading 70 ohms so that should be good. Any help would be appreciated TIA.
Square D 8536 Motor Starter
- Thread starter bdmitch
- Start date
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
has it quit working? OLs reset?
Is this a wild leg system?
I found 240 v starter coils hard to trouble shoot, I changed all 240 and 480 to 120.
Others will be able to assist
Is this a wild leg system?
I found 240 v starter coils hard to trouble shoot, I changed all 240 and 480 to 120.
Others will be able to assist
ptonsparky
Tom
- Occupation
- EC - retired
What is the applied coil voltage?. Forget voltage to ground. It's looking for 240 at the coil terminals. Check overload contacts, check any limit or control contacts. Voltage will read 240 if they are open.
Control fuses?
Control fuses?
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Then they are not from different phases.
ptonsparky
Tom
- Occupation
- EC - retired
Do not measure to ground.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
You may have a bad coil.
By the way what kind of siren does it run?
I had a civil defense air raid siren with a 7 1/2 hp roots blower. Could hear it 5 miles away
By the way what kind of siren does it run?
I had a civil defense air raid siren with a 7 1/2 hp roots blower. Could hear it 5 miles away
Well there's no neutral to measure too. And between B and C phase I have 240 at the main breaker
MTW
Senior Member
- Location
- SE Michigan
Measure B to C at the starter, not the breaker
They are from different phases. 1 is fed from B phase the other is From C phase and I have 240 between them where the power for the coil originated from.
MTW
Senior Member
- Location
- SE Michigan
Then measure across both sides of the overload contact, you should have full voltage from both sides to the opposite phase.
It is the big sirens up on poles for emergency services. The coil has 70 ohms. Maybe it could still be bad?
MTW
Senior Member
- Location
- SE Michigan
Don't go by the ohms. if you have 240V at the coil terminals, the coil is burned out, if you don't have 240V the something is wrong with the power, wiring or control contacts.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Don't worry about the coil until you measure 240V across it.