bjp_ne_elec
Senior Member
- Location
- Southern NH
OK Mickey - it's Tuesday and you're leaving us in suspense. What was the root cause?
control wiring problem
- Thread starter mickeyrench
- Start date
- Status
mickeyrench
Senior Member
- Location
- edison, n.j.
to make it short i found a wire going to #2 on the holding circuit had a slice in it . the wire is located behind the fuse block / starter area where it is hidden.
i cleared the wire from touching any metal and with the motor leads diconnected
[ because operations won't let me start motor until today] the starter operated each time i started it. 2x
the 120 v fuse was 3a. i put in 1a. also found bucket had 24v power when breaker was off. it appears to becoming from plc cabinet, this not indicated on print.
#2 wire was not connected backup yet,[ i was taken off to do something else] and i am hoping that was the cause of the problem.
will be back today.
i cleared the wire from touching any metal and with the motor leads diconnected
[ because operations won't let me start motor until today] the starter operated each time i started it. 2x
the 120 v fuse was 3a. i put in 1a. also found bucket had 24v power when breaker was off. it appears to becoming from plc cabinet, this not indicated on print.
#2 wire was not connected backup yet,[ i was taken off to do something else] and i am hoping that was the cause of the problem.
will be back today.
- Location
- Illinois
- Occupation
- retired electrician
The #2 wire on a standard start/stop circuit should be hot before the starter is pulled in. You indicated that the fuses blew when you pushed the starter in. Is the 24 volts on an aux contact to tell the PLC that the motor is running?
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Wouldn't you need to know which transformer lead is grounded to make such a conclusion?
- Location
- Illinois
- Occupation
- retired electrician
Larry, if the stop start control wires are on the grounded side of the control transformer, the installation is not code compliant. 430.73.
NEC 2008 divides 430.73 of the 2005 edition into two numbered paragraphs: 430.73 and 430.74... the latter being pertinent to your point. (Additionally, what was 430.74 is now 430.75 under the 2008 code.)
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Forgot to mention that only applies to remote control and not wiring internal to a bucket.
Nonetheless, typical bucket start/stop wiring is as depicted below...
mickeyrench
Senior Member
- Location
- edison, n.j.
I went in today connected the wire to the #2 terminal on the starter and the fuse blew again , disconnected it and starter works fine . wiring seems to be a two wire control , it is operated by hand-off- auto switch . the #2 wire goes to one of the six other contactors in the bucket with the starter. i guess i will wait to get a call that something is not working and finish the job. thanks for all the help. its great to have you guys when i am stuck.
- Location
- Illinois
- Occupation
- retired electrician
Now that is different. If the system is two wire control, and you have a conductor on the #2 terminal, it appears that they are using what is normally the seal in contact as an aux contact to control other loads or equipment. You really need the control drawing to troubleshoot this type of problem. If there is not one available you may have to trace all of the wires and make one.
ohm
Senior Member
- Location
- Birmingham, AL
Remember if the starters don't pull in completely (dirty, sticking, chattering, etc) they will draw much more current than normal. I would blow down the panel just for grins.
And, I saw a bad control transformer fool an army of electricians and engineers. Load it down with a bulb, just to eliminate it.
And, I saw a bad control transformer fool an army of electricians and engineers. Load it down with a bulb, just to eliminate it.
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