Reversing contactor hot

[scottyb]

Originally Posted by Sergio

Because of the massive current carrying capacity of the Normally Open Contacts, those contactors have pretty strong coils.

The Continuous duty models have a 20w coil and the Intermittent duty ones 60w.

I never measured the temperature of the operating coil, so I don't know how quick the temperature will climb while in operation.

You can certainly measure the coil resistance to make sure it is within tolerances.

Disconnect the wires from the small tabs of the coil and measure the resistance, the specs calls for approximately 140Ω.

I have done some testing on this unit. I believe coil temp raised 10º after 30 minutes of continuous activation. Contacts looked as new.

[Mlmill]

The problem is the wiring on the go-fast button. The connections on S1 and S2 on motor lay on same lug as ones coming from contactor. Is it possible that excess voltage is flowing back through these wires and getting back to contactor? Maybe a diode on the go-fast solenoid would stop this flow??

[Sergio]

Why do You think that is a problem?

When the "go fast" solenoid is not ON, it is the equivalent of those wires not being there.

I asked if You had wired it to the Contactor as it could have introduced a bad connection at the Contactor, but since the double lug is at the motor, if the connections are bad, the motor post would be getting hot.

The part getting hot is the Contactor coil from what you marked with an "X".

Are you running more than 48v on your cart?

[Mlmill]

I unplugged the activation wires connected to the momentary button for the go-fast and contactor ran much cooler (130-140F). Same result when I disconnected one of the big wires from the go-fast solenoid.
But when the go-fast is all wired up, the temp increases to 185F (that was without the reistor wired up between the big posts of the solenoid). I just installed this resistor a few days ago and greatly reduced the heat. That was the reason i figured a diode was supposed to be installed to stop flow - like the resister was reducing the flow

[Mlmill]

Forgot to answer last question: no, I am only running 48v. The go-fast solenoid is the old one that I was using from my previous 36v set-up, but the activation wires are tied to 4 of my new 8v batteries

[Sergio]

Disconnect one of the cables from the top of the 'Go Fast' solenoid and make sure the contacts are not welded already.

Set your Multimeter to resistance (ohms) and measure the resistance between the two big posts without pressing the button, it should be Open Line or "0L".

Then press the button and make sure it goes to 0Ω.

Also, make sure there is no voltage on the small terminals of the "go fast" solenoid when the button is not pressed.

[Mlmill]

Thanks. I will check that this evening when I get home, but if the contacts were welded wouldnt that mean that the go-fast would always be engaged? I dont think that is the case because i can hear the solenoid click when i press button, and i can definitely tell the cart picks up speed at that point.

[Sergio]

That is true, but then none of the variables you changed could have had any affect on the contactor temperature.

The amount of heat generated by the contactor coil is a function of the time it is engaged as well as the surround ambient temperature, perhaps Your testing procedure is changing every time which makes any cause and effect comparison between results invalid.

[Mlmill]

Originally Posted by Sergio

Disconnect one of the cables from the top of the 'Go Fast' solenoid and make sure the contacts are not welded already.

Set your Multimeter to resistance (ohms) and measure the resistance between the two big posts without pressing the button, it should be Open Line or "0L".

Then press the button and make sure it goes to 0Ω.

Also, make sure there is no voltage on the small terminals of the "go fast" solenoid when the button is not pressed.

Just performed this test. All checked out OK.

[Sergio]

I missed the first time You posted the picture (its sideways) that the SW202 is mounted upside down.

That is not recommended by the manufacturer since the plunger/contact hardware assembly is heavy and the Normally Closed contacts are only held in place by the internal spring when the solenoid is OFF.

Mounting it upside keeps gravity working against the spring and it could cause the Normally Closed contacts to bounce.