relays

[stilllearning]

Need some help with some relays I've been looking at , what function do the orange tabs have on the relays ? , are they to operate normally open and normally closed contacts on the relays ?

 

[Lucien Nunes]

Some relays do have a manual actuator for test and troubleshooting purposes, but it's not always an 'orange tab', it equally be could be a blue lever or a red button. They can be a menace when people poke around inside panels they don't understand, pressing randomly...

 

[tazz]

Very useful on old fire alarm panels, to prevent doors closures, plant shutdown etc when testing.
But can be a pain, if not reset when testing is completed.

 

[andyelectric]

Some relays do have a manual actuator for test and troubleshooting purposes, but it's not always an 'orange tab', it equally be could be a blue lever or a red button. They can be a menace when people poke around inside panels they don't understand, pressing randomly...

I remember a guy who in a fault situation shorted out a relay to get things back on track.. And sent a 4.5 inch artillery shell up the backside of another with 3000 psi of hydraulics behind it. That was a big oops.

 

[PEG]

Some relays do have a manual actuator for test and troubleshooting purposes, but it's not always an 'orange tab', it equally be could be a blue lever or a red button. They can be a menace when people poke around inside panels they don't understand, pressing randomly...

...Yes,had to do a fair bit of solder-scraping,after chaps have pressed the wrong two out of three manuals,on star/delta start equipment....mini Vesuvius :icon12:

 

[PEG]

I remember a guy who in a fault situation shorted out a relay to get things back on track.. And sent a 4.5 inch artillery shell up the backside of another with 3000 psi of hydraulics behind it. That was a big oops.

Lovely!...was it as troublesome to get them out as when you got 2 or 3 pellets jammed up yer air rifle barrel? :icon12:

 

[andyelectric]

Lovely!...was it as troublesome to get them out as when you got 2 or 3 pellets jammed up yer air rifle barrel? :icon12:

Best part of a day to retrieve the situation. This was in a loading hoist not into the actual barrel though.

 

[PEG]

Yes,i bet that was a relief...seen what a 12 guage does to a plugged barrel,can imagine the ordinance in question being a tad more costly...:icon12:

 

[Knobhead]

One of the worse or best things ever devised. Having spent many miserable hours finding where some muppet has used the override to get around a fault and not recorded it in the shift log, the worse things. When finding a fault, they’re the best.

Before relays with overrides became readily available we would remove the relay and use a 18” loop of singles to bridge out the relay. Anyone opening the panel could immediately see what had been done.
Somewhere in my tool chests I’ve still got the relays I made with the guts removed and mini toggle switches fitted. Very useful when commissioning a plant.

 

[Robotstar5]

Somewhere in my tool chests I’ve still got the relays I made with the guts removed and mini toggle switches fitted. Very useful when commissioning a plant.

Reminds me of using something like the lamp test button to simulate inputs when commissioning a PLC driven machine providing you remember to remove it from the program when finished. It gets interesting when someone tests the lamps and one of the motors starts indexing!