Forward/Reverse for J test

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BCJ

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I am working on doing my forward/reverse for my journeyman test. Everything on it checks out and is working properly, except I can push both buttons at the same time and both coils engage. My NC interlocks both open up so I'm really confused how power is getting to my coil. Any help is much appreciated. Thanks
 
What happens if it is running in forward and you push the reverse button....don't try this if the line side of the contactors are energized.
 
BCJ said:
I am working on doing my forward/reverse for my journeyman test. Everything on it checks out and is working properly, except I can push both buttons at the same time and both coils engage. My NC interlocks both open up so I'm really confused how power is getting to my coil. Any help is much appreciated. Thanks
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Drawing it out usually helps.

I prefer one side of an intelock switch connect directly to the coil it controls (which is never the coil which controls it). It's easier to verify nothing else can energize the coil.
 
Reversing contactors should have both mechanical and electrical interlocks. The mechanical prevent both contactors from closing at the same time. The electrical interlocks when wired properly will prevent energizing the coils at the same time.
 
templdl said:
Reversing contactors should have both mechanical and electrical interlocks. The mechanical prevent both contactors from closing at the same time. The electrical interlocks when wired properly will prevent energizing the coils at the same time.
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For a lot of journeyman's exams they do not let you use a forward/reverse contactor instead they require you to use 2 separate motor starters with a single overload. That is the way the test is set up for the Utah Journeyman's test.

Chris
 
I take it there is a "hands on" portion to the test where the OP lives?

What else may one expect to do for this hands on portion of test?
 
Smart $ said:
That should be the hold-in contact(s), as mentioned. As I stated earlier, one side of the interlock contacts get wired directly to the coil they control.

http://www.allaboutcircuits.com/vol_4/chpt_6/4.html
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That is the common place for the connection of the interlock contacts, but they can be placed elsewhere in the circuit and still work correctly.

I wonder if the OP placed them just to the right of the forward and reverse buttons but to the left of the conductor that goes to the seal in contact? If so, it may be possible that by pushing both buttons at the same time that the mechanical inertia would let both the forward and reverse contactors to "seal in".
 
don_resqcapt19 said:
I wonder if the OP placed them just to the right of the forward and reverse buttons but to the left of the conductor that goes to the seal in contact? If so, it may be possible that by pushing both buttons at the same time that the mechanical inertia would let both the forward and reverse contactors to "seal in".
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+1
(+1 == "me too")
 
Your circuit is operating correctly. That is the inherit nature of the mechanical parts.


If you wire up two contactors with a normally closed contact in series with each coil as wire in your starter in parallel
and apply power to them the fastest acting contactor will win the race.

It would be impossible or an accident to push the two push button that accurately in time to drop them both out with the normally closed contacts.

Both contactors should see enough voltage to try to pull in.But only one should win the race and
continue to stay in after the start buttons are released.

If its wire correctly and your normally closed contacts open as they should only one would stay engaged.


Ronald :)
 
ronaldrc said:
Your circuit is operating correctly. That is the inherit nature of the mechanical parts.


If you wire up two contactors with a normally closed contact in series with each coil as wire in your starter in parallel
and apply power to them the fastest acting contactor will win the race.

It would be impossible or an accident to push the two push button that accurately in time to drop them both out with the normally closed contacts.

Both contactors should see enough voltage to try to pull in.But only one should win the race and
continue to stay in after the start buttons are released.

If its wire correctly and your normally closed contacts open as they should only one would stay engaged.


Ronald :)
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It is not impossible if you wire it how I described it.

If you put the NC contacts as the last item before the coil, then it is impossible to pull and latch both in at the same time. As you said one will win the race.

However if you put the NC interlock contact in series with the start buttons and in parallel with the seal-in contacts it is very possible to push the buttons at the same time and latch both contactors in.
 
I agree because when you push the start button thats shunts your normally closed interlock contact.

But if it is wired correctly as you described it is impossible for both to stay closed or maintained.

Ronald :)
 
ronaldrc said:
I agree because when you push the start button thats shunts your normally closed interlock contact.

But if it is wired correctly as you described it is impossible for both to stay closed or maintained.

Ronald :)
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Actually the NC interlock contact is not shunted by the start button in my description...both the NC interlock contact and the start button are shunted by the seal-in contact.

I decribed the hook-up with the NC contact in series with the start buttone because I can't think of any other hook-up that would let you pull in both of the contactors at the same time by pushing the buttons at the same time and have the circuit work correctly it you pust the buttons one at a time. I though maybe it would help the OP figure out why his circuit does not work as itended.
 
ronaldrc said:
I agree because when you push the start button thats shunts your normally closed interlock contact.

But if it is wired correctly as you described it is impossible for both to stay closed or maintained.

Ronald :)
Click to expand...
Look at the first diagram on the web page I posted the link for earlier. I believe what Don is describing is the seal-in contact connections at 4 and 5 moved to the other side of the respective interlock contacts.
 
Smart

As usual I didn't read the post that good. But I'll take Dons word on it.
I know Don knows the difference between a seal or hold in contact, and a
normally closed Interlock.

We all know there is some out of place or it would work properly but its a
good thing they didn't have the lines on the starters wired together, if so I
know it wouldn't stayed maintained long.

Ronald :)
 
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