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Ac contacter testing
- Thread starter tacoma
- Start date
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- Apr 30, 2015
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One thing I learned recently about these contactors is if the test button is sucked in they are often damaged internally
And if one goes the others are often not far behind
I have no idea how reliable these are, but it's the only one available that matches the original
Unless you want to order from China and wait a month
And if one goes the others are often not far behind
I have no idea how reliable these are, but it's the only one available that matches the original
Unless you want to order from China and wait a month
Last edited:
- Joined
- Apr 30, 2015
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- 12,473
I would measure your transformer and see if it really has a 24 v output- that would be the preferable tap to use
instead of 29 v
Most places in the US have 240 volts now rather than 220, which could cause the 29 volt output to be even higher
causing the contactors to overheat and fail prematurely
I wonder how many lathes out there are cooking their contactors? mmm teriyaki
instead of 29 v
Most places in the US have 240 volts now rather than 220, which could cause the 29 volt output to be even higher
causing the contactors to overheat and fail prematurely
I wonder how many lathes out there are cooking their contactors? mmm teriyaki
Last edited:
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- Apr 30, 2015
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According to the schematics I've seen there is a 24 volt tap on the transformer that's not used.
Yours has an empty terminal that says 0 so I don't know for sure if it's a thing or not- have to measure to find out.
When the residential power was closer to 220v (in the before-time) the 29 volt tap might have been ok
but not today- 240v is pretty much standard, in most places in the US anyhow.
Most contactors will pull in at a considerably lower voltage than rated- down to around 21 volts or less for the 24 volt units
Running them over 24 is just overheating the coils and cooking the plastic parts inside, especially since they are in an enclosure with a
heat source (transformer) and little to no airflow
It could be that the transformers they use don't have good load regulation, and that plus the normal drop when the motor starts
led the factory to use the higher voltage to prevent contactor drop-outs and chattering. Only way to find out is to move the wire over
and see for yourself. Can't hurt
Yours has an empty terminal that says 0 so I don't know for sure if it's a thing or not- have to measure to find out.
When the residential power was closer to 220v (in the before-time) the 29 volt tap might have been ok
but not today- 240v is pretty much standard, in most places in the US anyhow.
Most contactors will pull in at a considerably lower voltage than rated- down to around 21 volts or less for the 24 volt units
Running them over 24 is just overheating the coils and cooking the plastic parts inside, especially since they are in an enclosure with a
heat source (transformer) and little to no airflow
It could be that the transformers they use don't have good load regulation, and that plus the normal drop when the motor starts
led the factory to use the higher voltage to prevent contactor drop-outs and chattering. Only way to find out is to move the wire over
and see for yourself. Can't hurt
Last edited:
This ^^^^^ appears to be a problem across the board as technology changes. Where battery cell voltages were 1.25 volts, I have seen them as high as 1.8V. Just an observation.
- Joined
- Apr 30, 2015
- Messages
- 12,473
Another note about contactors: The ones in your machine are a 7-pole design and not common. With a couple wiring changes 4-pole units
could be used instead- Some of the systems are unnecessarily complicated; no reason IMO
For example, yours runs the motor power thru KM1 which is redundant- It could be simplified considerably
I'm thinking of doing a sketch that would show how to do that- just for kicks
could be used instead- Some of the systems are unnecessarily complicated; no reason IMO
For example, yours runs the motor power thru KM1 which is redundant- It could be simplified considerably
I'm thinking of doing a sketch that would show how to do that- just for kicks
Last edited:
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- Jan 2, 2019
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- 7,322
When I bought my current lathe it had one of these control boxes. It worked when I picked it up but was unreliable as soon as I got the machine home.
I’d already put a VFD and 3phase motor on my Seneca Falls, and have some experience with electronic/electrical troubleshooting so I knew what path I wanted to take.
Sure, it was an extra $300 I would have rather not spent. But, not having to wrestle with 30 year old control systems, and getting variable speed at the turn of a knob is worth it for me.
John
I’d already put a VFD and 3phase motor on my Seneca Falls, and have some experience with electronic/electrical troubleshooting so I knew what path I wanted to take.
Sure, it was an extra $300 I would have rather not spent. But, not having to wrestle with 30 year old control systems, and getting variable speed at the turn of a knob is worth it for me.
John
Its finally powered up with green light on that's about all I have. It has 220 to far left relay which is also spliced to supply transformer.
Probing all the other wires on that relay shows 0 , selector switch engaged. No power to any of the other relays either.
Thermal switch has continuity across it.
The green light is always on. There is not an on/off control for main power
Suggestions please ?
Probing all the other wires on that relay shows 0 , selector switch engaged. No power to any of the other relays either.
Thermal switch has continuity across it.
The green light is always on. There is not an on/off control for main power
Suggestions please ?