Contactor response time

[sysrq]

Are the contactor response times significantly different between for each manufacturer?
For certain types of relay logic it's quite critical (drop-out and pick-up time, NO/NC sequence).
Usually NC contacts are disconnected first before NO contacts are connected.
Had to replace 4NO 4NC Siemens 3TH82 44-0B contactor for Schneider Electric one with auxiliary contacts on Behringer HBP 260/340/420 band saw due to lack of continuity on some contacts.
Now it turns of when auto mode button is pressed. I guess Schnieder Electric CA3KN22-BD3 has faster response time since it's physically smaller, or different NO/NC configuration is an issue.

 

[Lucien Nunes]

Times differ, although not usually by enough to affect a well-designed control system. Properly engineered controls should not rely on races between elements because of the wide tolerance, but rather on contact sequence. This should not vary from one maker to another for the same type of device, however the timing of auxiliary vs. main contacts might unless clearly specified. It's not a parameter that I would want to rely on in a design unless necessary (e.g. proving disconnection).

 

[sysrq]

Times differ, although not usually by enough to affect a well-designed control system. Properly engineered controls should not rely on races between elements because of the wide tolerance, but rather on contact sequence. This should not vary from one maker to another for the same type of device, however the timing of auxiliary vs. main contacts might unless clearly specified. It's not a parameter that I would want to rely on in a design unless necessary (e.g. proving disconnection).

Right okay, thanks for answer. Problem might persist due to heightened contact resistance on other contactors (when measured with multimeter), or there might be messed up wires due to lack of labelling.
Will have to look for Behringer HBP 260A 1992 band saw electrical wiring diagram.
This one is old model without a PLC so there are a lot more things that can go wrong and troubleshooting is more complicated as well to some degree.

 

[Bobster]

Relying on drop out/engage times for a control system to work properly must be one of the stupidest things I've ever heard of in design!

As soon as 1 spring wears slightly, thats it, all to pot!

 

[Darkwood]

I would have thought a dated machine like you have would be quite easy to follow wiring wise without trying to locate any wiring diagrams, they were built robust but operationally quite simple as H&S that's applicable now was just a pipedream in them days.

You say the wiring might be mixed up..
Does this mean its not been working for a long time or someone has been fiddling with the wiring recently?

Regarding contact response times, agree with above, any design system shouldn't be suseptible to slight delay in response times, operational order and sequence should be fail safe if it would cause a hazard and where the nature of the machine means it might be an issue then extra redundancy or safety systems should be implemented.

If this is just an operational problem where something isn't happening when it should then its may be the case you have to cable trace and work out the wiring, its not too common to find available wiring plans for old stuff especially if they are built abroad.

 

[sysrq]

Relying on drop out/engage times for a control system to work properly must be one of the stupidest things I've ever heard of in design!

As soon as 1 spring wears slightly, thats it, all to pot!

I have the same thoughts. Germans usually design everything properly. I had no other choice but to buy some cheaper/smaller contactor.

The other option is to repair the old one, only thing is usually it's not worth the hassle.

 

[netblindpaul]

It's probably a crossed wire, or has a wire pulled out somewhere else when you have been moving things around in the panel to fit the new contactor?

 

[sysrq]

It's probably a crossed wire, or has a wire pulled out somewhere else when you have been moving things around in the panel to fit the new contactor?

It might be the case since it shuts itself down as well (when switching to automatic mode) in case of a disconnected work-piece sensor switch, it's connected in series with that particular contactor coil.
Now we are playing a guessing game. There is no other way but to fiddle around with it for a while until something pops up.

 

[netblindpaul]

No, you don't need to fiddle around.
It's NOT a guessing game either.
You need to trace the wiring though the panel and understand how the machine circuit works and sort the wiring out so it is the way it should be, as it was designed, if, it's wrong.
Then you can look for any faults.
Get yourself a pen & paper and reverse engineer the circuit.
Simples.
If you had been smart you would be SURE that the wiring on the contactor you changed was correct.
That is what sharpies and white insulation tape are for!

 

[sysrq]

No, you don't need to fiddle around.
It's NOT a guessing game either.
You need to trace the wiring though the panel and understand how the machine circuit works and sort the wiring out so it is the way it should be, as it was designed, if, it's wrong.
Then you can look for any faults.
Get yourself a pen & paper and reverse engineer the circuit.
Simples.
If you had been smart you would be SURE that the wiring on the contactor you changed was correct.
That is what sharpies and white insulation tape are for!

I think it will be quite hard to reverse engineer the circuit without any mistakes in this case since there are at least 15 contactors, 8 time delay relays and 7 push-buttons with bunch of unmarked wires squeezed in to the wiring duct.

Agree, sharpies and white inslulation tape is better than reconnecting wires one by one even if there are just a few wires.

 

[netblindpaul]

It may not be easy, but that device count is not really that much.
This is why we can get paid what we do get paid for doing machinery, in other words 2 - 3 times what you can get for domestic installs, because we can sort out rats nests like this.
This is how I earn my living, often picking up the pieces after some muppet has mucked it up.
Not you I hasten do add, just go back to where you started with your site notes and your wire markings and check the contactor (s) you replaced, then trace the wires from those connection points, and knowing the function of the devices that they are connected to you will begin to see the circuit so you can then draw it out on paper if you can't see it in your mind, and you'll soon see what has gone wrong.

I think my worst is over 100 contactors, no wiring diagram, no PLC printout, 40+ push buttons, no CNC control programmes, but, if you follow the wiring you can decide on what is what.

 

[Darkwood]

It may not be easy, but that device count is not really that much.
This is why we can get paid what we do get paid for doing machinery, in other words 2 - 3 times what you can get for domestic installs, because we can sort out rats nests like this.
This is how I earn my living, often picking up the pieces after some muppet has mucked it up.
Not you I hasten do add, just go back to where you started with your site notes and your wire markings and check the contactor (s) you replaced, then trace the wires from those connection points, and knowing the function of the devices that they are connected to you will begin to see the circuit so you can then draw it out on paper if you can't see it in your mind, and you'll soon see what has gone wrong.

I think my worst is over 100 contactors, no wiring diagram, no PLC printout, 40+ push buttons, no CNC control programmes, but, if you follow the wiring you can decide on what is what.

Almost like I wrote that post ... takes years/decades to get an analytical mind but once you do you can almost write your own cheques.

 

[sysrq]

Almost like I wrote that post ... takes years/decades to get an analytical mind but once you do you can almost write your own cheques.

True, the more you learn the less you understand and if you manage to get something done once it doesn't mean you will be able to do it every time. The hardest thing is to always start with the right mindset.

 

[sysrq]

Thanks for answers. Found one loose screw on timer relay, now it works.

 

[Bobster]

I hope that didn't take 4 weeks haha

 

[sysrq]

I hope that didn't take 4 weeks haha

No it didn't as I was busy with other things in the meantime. I was not allowed to work on it everyday anyway.

 

[sysrq]

Unfortunately it was too good to be true, now after a while it turns itself off again when the automatic cycle button is pushed (yellow pilot light briefly comes on then goes off). We have ordered service manual, maybe it will help to some degree.
When one of time delay relays are being tapped then it turns off the main 24 VDC supply contactor.

 

[sysrq]

Received the wiring diagram with user manual not long ago. Seems like latching on automatic mode circuit is working. I think there might be some unrelated or unobvious cause, something is still in a semi-broken state.
Not sure if it's advisable to show the wiring diagram according to intellectual property law.

 

[sysrq]

Another thing is there is missing NO K33.1 contact in series between K33 and K33.1 coils (wiring diagram incorporates three different models in one).

 

[sysrq]

Thanks for answers everybody. Turns out one contactor was pressing too much against the time delay relay.
One link on the terminal block was bad as well.