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.