Whats wrong with this?
- Thread starter ronaldrc
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russ
Senior Member
- Location
- Burbank IL
Re: Whats wrong with this?
should the N.O. contact on the right be labeled M.
Russ
should the N.O. contact on the right be labeled M.
Russ
Re: Whats wrong with this?
Russ is close, look at the start button when you push it, it energizes M which is the starter coil which starts the motor.
The second post was right thats right the TC can't start timing out because it never sees power.
I don't know what kind of delay this is pneumatic or solid state. Either way the NO TC contact is in series with TC coil.
The TC coil can't be energized this way because of NO TC.The motor would continue to run with the resistors in the rotor circuit it would never pick up to full speed.
The only other answer is it is a simplified diagram and not showing all the controls but I don't think so because it doesn't mention that and it doesn't show any wire conn. take offs for other controls.
Ronald
[ September 01, 2003, 08:33 PM: Message edited by: ronaldrc ]
Russ is close, look at the start button when you push it, it energizes M which is the starter coil which starts the motor.
The second post was right thats right the TC can't start timing out because it never sees power.
I don't know what kind of delay this is pneumatic or solid state. Either way the NO TC contact is in series with TC coil.
The TC coil can't be energized this way because of NO TC.The motor would continue to run with the resistors in the rotor circuit it would never pick up to full speed.
The only other answer is it is a simplified diagram and not showing all the controls but I don't think so because it doesn't mention that and it doesn't show any wire conn. take offs for other controls.
Ronald
[ September 01, 2003, 08:33 PM: Message edited by: ronaldrc ]
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: Whats wrong with this?
TC can never be energized as the N/O contactes would prevent it
TC can never be energized as the N/O contactes would prevent it
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: Whats wrong with this?
Ronald your are quick on the key LOL
Ronald your are quick on the key LOL
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: Whats wrong with this?
templdl
There is no requirement in Art 430 for fuses in a control circtuit tapped from the motor branch circuit, as shown here. See section 430.72(A). However if fuses are installed then the motor control circuit follows the rules in Art 725, see last sentance in 430.72(A)
templdl
There is no requirement in Art 430 for fuses in a control circtuit tapped from the motor branch circuit, as shown here. See section 430.72(A). However if fuses are installed then the motor control circuit follows the rules in Art 725, see last sentance in 430.72(A)
Re: Whats wrong with this?
Thanks for confirming the circuit is drawn wrong.
Truth is if where a pneumatic starter with two pneumatic NO contacts that NO contact wouldn't even be needed.
I no everyone makes mistakes but the bucs we pay out for these books you would think they could look over them a little better.
Ronald
Thanks for confirming the circuit is drawn wrong.
Truth is if where a pneumatic starter with two pneumatic NO contacts that NO contact wouldn't even be needed.
I no everyone makes mistakes but the bucs we pay out for these books you would think they could look over them a little better.
Ronald
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: Whats wrong with this?
I think I was typing while you were I'm just not as fast LOL
I think I was typing while you were I'm just not as fast LOL
Ed MacLaren
Senior Member
Re: Whats wrong with this?
I wonder why the contact which is (erroneously) marked "TC" is shown in a seperate enclosure, and what operates it?
The way it is wired, it energises the TC coil.
And the two contacts above the TC coil should be identified "TC".
Here are a couple of different Wound Rotor Motor controls that I think will work OK.
One is a 3-step starter, and the other is a 3-speed controller.
Ed
I wonder why the contact which is (erroneously) marked "TC" is shown in a seperate enclosure, and what operates it?
The way it is wired, it energises the TC coil.
And the two contacts above the TC coil should be identified "TC".
Here are a couple of different Wound Rotor Motor controls that I think will work OK.
One is a 3-step starter, and the other is a 3-speed controller.
Ed
Re: Whats wrong with this?
Ed thanks for the diagrams look good to me.
Magnetics made things easy.Large solid state are functionly better but I don't trust them. I like mechandical contacts for isolation.
Of course thats why we have disconnects I guess.
Like I said I'm not certain about that delay circuit on that drawing if there are more controls not shown? If so it usually says so.
Remember the old oil type manual like a transfere switch.Those where the days.
Ronald
Ed thanks for the diagrams look good to me.
Magnetics made things easy.Large solid state are functionly better but I don't trust them. I like mechandical contacts for isolation.
Of course thats why we have disconnects I guess.
Like I said I'm not certain about that delay circuit on that drawing if there are more controls not shown? If so it usually says so.
Remember the old oil type manual like a transfere switch.Those where the days.
Ronald
david
Senior Member
- Location
- Pennsylvania
Re: Whats wrong with this?
Could the TC NO contact be some kind of centrifugal switch?
Could the TC NO contact be some kind of centrifugal switch?
Re: Whats wrong with this?
David thats a good call and I believe it is right. I just reread all the information on those pages it didn't mention a centrifugal
switch.
But I am going to assume it is a centrifugal switch untill someone tells me different.
It does show it in a separate enclosure.
Thanks:Ronald
David thats a good call and I believe it is right. I just reread all the information on those pages it didn't mention a centrifugal
switch.
But I am going to assume it is a centrifugal switch untill someone tells me different.
It does show it in a separate enclosure.
Thanks:Ronald
Re: Whats wrong with this?
Tom Baker,
My referrence is NFPA 79 (my copy is 1997), 8.9 Control circuit conductors. Your statement is correct when the circuit meets the requirements of the exceptios as I understand it.
8.9 General, and 8.9.2 Conductor Protection. Both 8.9.2.1 and 8.9.2.2 both state that they shall be protected in accordance to their ampacities or not more than a 20a rating for conductors #14 and smaller.
However, if the control circuit falls within the exceptions that are incuded in this section then and OCPD is in fact not required as you have stated.
Tom Baker,
My referrence is NFPA 79 (my copy is 1997), 8.9 Control circuit conductors. Your statement is correct when the circuit meets the requirements of the exceptios as I understand it.
8.9 General, and 8.9.2 Conductor Protection. Both 8.9.2.1 and 8.9.2.2 both state that they shall be protected in accordance to their ampacities or not more than a 20a rating for conductors #14 and smaller.
However, if the control circuit falls within the exceptions that are incuded in this section then and OCPD is in fact not required as you have stated.
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