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NEED A RELAY TO DRIVE HIGH VOLTAGE (240 v)

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SISWANTO

SISWANTO

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neon sign solid state relay -chevy

Dear All,
I need a relay to drive neon lamp 240 volt (inductive)
I had bad experience with relay board, because inductive load.
please help me.



Salam
Siswanto
 

is 240 a high voltage?

i think you should calculate the current of the lamp and then you can choose the relay that is combatable with it
 

sami123qa said:
i think you should calculate the current of the lamp and then you can choose the relay that is combatable with it
Click to expand...

I thing my problem isn't because the current, but the load is Inductive Load.
It is hold and keep energi at the coil at ON condition, and release spike energi
when it turned OFF to the relay. It is my big problem.



Salam
Siswanto
 

You are using diodes antiparallel to the relay to protect it from voltage spikes when you turn the relay off, correct?
 

Hello,
It sounds to me as if you are using a solid state relay board. Inductive loads may not allow such relays to turn off. It seems very improbable that a mechanical relay gets stuck if contacts are not welded.
Antiparallel diodes are a must driving mechanical relays anyway. Mount it close to the relay coil to avoid the turn off energy travel on your board.
BTW, I assume you are talkink about some sort of neon sign..... Neon lamps are usuallly a very high resistive impedance.

Best regards
 

Relays are a bad thing to switch inductive loads.

Maybe you can switch this with a triac and a speial RC-network. But we switch in a professional product with MOSFETs at 90° after zero crossing voltage (== zero crossing current) then is no energy in the inductive load and you have no spikes (we switch valves with AQY214EHA).

Gomez
 

try to connect a small value capacitor (nF) across the relay contact, it should reduce sparking across relay contacts with inductive loads.

a cheaper subustitue to solid state relay is a triac and an optotriac set. Triac may be like the BT138 and the opto like MOC3021. The opto datasheet is very helpful.
 

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