Faulty? NVR Switch

[Gerard O’TooleParticipant @gerardotoole60348]

Query if new switch is faulty

[Gerard O’TooleParticipant @gerardotoole60348]

I am trying to fit an NVR Switch ,with Emergency stop, to an older lathe. I have checked the wiring against diagram and against other advice here and elsewhere on the internet and i believe i have the switch wired correctly.

However the switch does not 'latch on' ( if that is the correct term ). i am actually testing with a 220v lamp and when i press the 'on button' the lamp will light but goes out as soon as I take my finger off the 'on button'.

I suspect it is faulty but wanted to check if I have wired it incorrectly.. There is a small fifth terminal on the NVR switch which is not connected and i wonder if that is the problem..

Any help would be much appreciated. The photograph shows the wiring

The NVR switch is marked CK21 .

Thanks

Gerard

[Andy CarruthersParticipant @andycarruthers33275]

There should be a link between Pins 5 and 3, loop with piggy-back connector – supplies current to hold-on relay inside switch

[kevin laxonParticipant @kevinlaxon28008]

there should be alink wire from pin 5 to either 1 or 3,there should be a schematic on the side of the relay.Kevin.

[Gerard O’TooleParticipant @gerardotoole60348]

Thank you both, Andy and Kevin,

I will rewire and hopefully get it working

I really appreciate the help

Gerard

 

Edited By Gerard O’Toole on 22/04/2021 21:04:15

[BazyleParticipant @bazyle]

NVR switches of this general type come in two forms. One (yours) has the extra terminal so that extra interlock switches can be added into the circuit.

[SillyOldDufferModerator @sillyoldduffer]

One mistook, as already explained the latching coil isn't connected.

The other point is the Normally Closed emergency off switch is wired to break the Live input. This means the switch contacts have to be rated to carry the full load to avoid them welding closed.

The version of the circuit below avoids that by only using the NC switch to break the latch circuit, which requires a much smaller current. Note in this configuration the NC switch is wired to the output Live, not the input as it is at the moment.

In the example below, the unused terminal in Gerard's photo is marked A1. It allows the relay coil ( U< ) to be energised to latch the manual contacts: the other side of the U< coil is connected internally to input neutral inside the switch.

Comment: There's something to be said in favour of the emergency stop being wired to disconnect the live input entirely (provided the switch is meaty enough not to weld!). There's also a version of the circuit wired as Gerard has it with a hefty NC switch on the input, plus one or more smaller NC switches in series with the latch coil. The low current switches are typically connected to guards, stopping power being applied until everything is safe.

Dave

Edited By SillyOldDuffer on 23/04/2021 09:12:06

[kevin laxonParticipant @kevinlaxon28008]

after altering the wiring you must activate the switch & then switch the power feed off & back on to confirm it resets,using the power feed & output the wrong way round will cause the contactor to pull in as soon as power is applied.

[Gerard O’TooleParticipant @gerardotoole60348]

Thanks to everyone for all the adivce.

I have rewired the switch and fitted to the lathe and everything is working as it should.

Much appreciate all the help

Gerard

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