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24 Volts Operated Contactor Switching Circuit

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gravi

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Dear EDA Board,

I just wanted to confirm whether this circuit will do good to switch ON/OFF Contactor which operates with DC Coil Voltage.


Thanking You,
Ravi Kumar Gangumolu.
 

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FvM

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Q9 base current is unreasonably high, R9 and R10 power dissipation too. You can scale it down by a factor of 10 to 50.
 

gravi

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Hi,

Yes I will replace 120 Ohms with 2.2 K and 1 K with 10 K but, It this the right circuit to drive contractors, do we have any better circuits to drive dc coil contactors.

Thanking you,
Ravi Kumar G.
 

FvM

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I just noticed that MCLR pin most likely means 3.3 or 5V input voltage. Increasing the resistor seems still reasonable. You didn't tell the coil resistance, so we can't determine correct dimensioning.
 

gravi

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Dear FvM,

We will use 2K resistor between Q10Base and Mclr Pin, We are not sure about coil voltage, these are general contactors with 24 Volts Coil to operate. To the best of my knowledge it consumes hardly 100mA so I think we could eliminate Q9, Only one transistor will do to drive Contactor.


Thanking You,
Ravi Kumar G
 

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