I think I have a burned out relay

[Eremius]

If it was me I'd just replace the contactor, overload heater, switches, and transformer. Rewire the whole thing in the process. You have old heat damaged components, corroded terminals, and jumpered heaters. It'll cost you a bit of money, but if you have some feel for electronics it is relatively easy.

So the only question is with two motors ... do both motors run at the same time? Or is the photos shown of only one motor's control circuitry? *Ideally* the two motors would each have their own overload heater, set for their Full Load Amps (FLA) rating. If both motors run at the same time, you can use one 4 pole contactor rated at combined load, then split the power after the contactor through separate overloads to each motor. The control circuit becomes x----Stop----Run-----OL1-----OL2-----contactor coil-------x
Where x is the two 120v outputs of the transformer,
Stop is just the stop switch
OL1 is the switch contacts on the overload heater to motor 1
OL2 is the switch contacts on the overload heater to motor 2
Run is a little trickier, it is

--RS--
| |
--| |----
| |
--C4--


Basically the run switch (RS) in parallel with the 4th set of contacts on the contactor (C4).

Hopefully in this case C4 doesn't correspond to explosives

Ah well, the html processor eats my spaces on the RS/C4 diagram. Apparently the [PRE] tag doesn't work here. Grr.

I am leaning toward just replacing everything as it has been hacked on for who knows how long and I believe all the protections have been taken out.

I will probably salvage the transformer as I *just* put it in.

Yes, both motors usually run at the same time. The upper motor should be powered from the main circuit as it shouldn't ever be able to run without the whole mill being powered on. It runs only the vertical spindle. The main motor powers the hydraulics of the mill (travel, lubrication, etc). The photos are only showing the primary control circuitry.

The secondary motor has it's own switching and contactor but, like the primary, it has been jumpered out. It uses a 2P2T switch to control forward and reverse on the spindle.

 

[Eremius]

Whee. So it's been a fun couple of weeks. I've been busy changing jobs so, yeah, I've been distracted.

In any case...

So here is what I *think* I will need:

1x main contactor
1x auxiliary contactor
1x three pole breaker (15A)

I am planning on going all DIN rail stuff.

I will be reusing the transformer I have as it was replaced less than a year ago.

The motors are both 3HP (images in another post).

What am I not thinking about?

 

[Eremius]

Ok, so doing a little more reading, I will want that contactor to have an auxiliary contactor that will be for the motor control circuit.

I *think* this list covers everything except possibly an overload relay. Suggestions?

Am I missing anything here on the lower controls?


If I am getting close on this I should probably start talking about the upper controls. The upper motor controller uses a 2P2T switch for forward and reverse. I don't have any clue what I need for a controller here.

 

[rabler]

Generally, you use a 4 pole contactor. The 4th pole is connected in parallel with a momentary contact normally open "run" switch. This acts as a safety feature, if the power dies, the contactor opens and turns it off. There are other ways to wire it but that is how your original was done. This should allow you to keep your front end switches and wire things up very close to one-for-one. Your stop switch is a momentary contact normally closed.

You don't need a breaker, that is covered by your wall panel. You do need the overload, and probably want to order them at the same time as the contactor since the overload is typically an accessory, so you need to match brands.

 

[rabler]

Ok, so doing a little more reading, I will want that contactor to have an auxiliary contactor that will be for the motor control circuit.

My post of a few minutes ago was looking at your schematic and post #32. You have got the right idea. Typically vendors will just sell that as a 4 pole contactor. There are such things as 3 pole contactors with (accessory) auxiliary contacts, but l believe the 4 pole contactor will be cheaper.

I may miss your posts depending on how busy I am in any given time period. Don't be afraid to message me directly if you need help.

 

[sdelivery]

The above post are pretty accurate except for install a main breaker in your panel.
The circuit breaker in your house or garage is meant for the wiring not for any attached load.
Additional breaker for control voltage from the transformer secondary output is highly recommended.
I typically buy all the above components from either Automation Direct, marshall Wolf,
Circuit breakers are inexpensive and can be a life saver.

 

[Eremius]

The above post are pretty accurate except for install a main breaker in your panel.
The circuit breaker in your house or garage is meant for the wiring not for any attached load.
Additional breaker for control voltage from the transformer secondary output is highly recommended.
I typically buy all the above components from either Automation Direct, marshall Wolf,
Circuit breakers are inexpensive and can be a life saver.

There is a 20A 3-pole breaker specified on that list for just that purpose.

 

[rabler]

The above post are pretty accurate except for install a main breaker in your panel.
The circuit breaker in your house or garage is meant for the wiring not for any attached load.
Additional breaker for control voltage from the transformer secondary output is highly recommended.
I typically buy all the above components from either Automation Direct, marshall Wolf,
Circuit breakers are inexpensive and can be a life saver.

I don't think they are required even by modern safety standards, such as UL. Since the wiring is in a metal cabinet is it really even a safety issue? (honest question, what safety issue does it address)

It can't hurt other than a very small cost. My understanding is you put fuses/breakers in an appliance when you're trying to protect internal components from damage. Which for example is what overload/heaters do for the motor. But when the cost of the components (such as a transformer) are on par with the cost of the breaker, it seems like diminishing returns.

That said, do whatever makes you feel safe. I certainly don't want any liability!!!

 

[Papa Charlie]

Regardless of the location, the breaker is to protect you from shock should the wire, switch or system short out. Once it hits that panel, everything that has continuity to the box is subject to voltage.

 

[sdelivery]

UL isn't involved with machine tool certification. UL certification requires a manufacturer to provide a sample product for testing.
Circuit breakers in homes and businesses are sized based on the conductors ampacity. They are there to protect the wiring during an over current situation. This is per the National Electric Code.
Circuit breakers in machine tools are there for that purpose as well.
An overcurrent condition can melt wires (perhaps energizing the machine cabinet or more) but primarily to protect from a melt down that could start a fire.
I have seen and repaired the first condition and I have seen the result of the second. They scrapped the machine.
An average single pole Circuit breaker for a control Circuit up to 10 amps is between 7.00 and 15.00 dollars, depending on the size of the control transformer I would guess a small one to be about 75.00 to 100.00.
The cost of a fire?