Fitting dol contactor for 415 v3 phase fans

[seadog60]

Dayo it has just the start stop

 

[seadog60]

Sorry just the 0ne start stop

 

[Dayo]

well you can get away with a 415 volt dol unit but you will have to state you are not using 110 volt to cover yourself.
you would have to use a transformer to step down from 415 or 230 to 110 volts then this 110 volts is your control voltage powering the contactor coil via start stop & emergency stop buttons. if they wanted remote stop buttons in the future it may not be safe to run 415volt cables in the industrial unit

 

[seadog60]

Thanks Dayo is there a regulation that states it must be 110v because i haven't read it?

 

[Dayo]

no most coils controlling motor / fans are the same voltage as the motor / fan they are controlling especially when there is only one start stop unit.
if you think about it there is one cable coming in to the dol starter and one cable leaving, both are carrying 415 volts 3 phase

 

[seadog60]

I have wired loads of dol 3 phase motors up useing 415v coil so this was new to me.I shall find out tomorrow but i just wanted to know if it was a new regulation i had missed.
Thanks

 

[steveautomation]

hi seadog60,

I used to wire / install / commission control panels a while back and the reason lots of control panels / motor circuits have 110v or 24vdc coils is to reduce the risk from a safety aspect.

The reason they did this was because the start / stop pushbuttons were normally mounted on the metal doors of the enclosure and by wiring the coils in 24vdc you would only have a potential of 24vdc at the door or if the control circuit was wired in 110v you would only have the potential of 55v at the door (usually a centre tapped transformer, same principal as your 110v yellow site leads)

If you need a hand with wiring diagrams etc let me know and i am more than happy to help.

Steve.

 

[Knobhead]

hi seadog60,

I used to wire / install / commission control panels a while back and the reason lots of control panels / motor circuits have 110v or 24vdc coils is to reduce the risk from a safety aspect.

The reason they did this was because the start / stop pushbuttons were normally mounted on the metal doors of the enclosure and by wiring the coils in 24vdc you would only have a potential of 24vdc at the door or if the control circuit was wired in 110v you would only have the potential of 55v at the door (usually a centre tapped transformer, same principal as your 110v yellow site leads)

If you need a hand with wiring diagrams etc let me know and i am more than happy to help.

Steve.

Sorry to correct you but nearly all 110V control systems are end tapped to earth. The reason being that an earth fault could hold a coil in making the e-stop inoperative.

 

[Engineer54]

If you have a Specification that states a 110volt control is to be utilised, then that is what you ''Must'' provide!! Standard fan control panels from the fan manufacturers are available off the self, for most common control voltages. If you are supplying the material for this job, contact the manufacturer. If your not supplying the material, then advise who ever is, that you need a 110volt fan control panel, to conform with project specifications!!!

 

[seadog60]

Thanks guys i have it sorted now.I have got a firm to make me 2 control panels for the fans.

 

[steveautomation]

Sorry to correct you but nearly all 110V control systems are end tapped to earth. The reason being that an earth fault could hold a coil in making the e-stop inoperative.

Hi Tony,

Thats the way my old gaffer used to get us to wire them, but when we wired in the e-stops (usually via a pilz safety relay) it would kill both the legs of the 110v so therefore isolate them completely under an e-stop situation.