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Microcontrollers reset when switching Contactor

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Hi,

When I am switching Contactors, Micro controller is getting reset, How to over come this.

Thanking You,
Ravi Kumar
 

Have a look at the micro power supply lines. There is probably either a dip or huge spike when the contactor switches. You need to add some filtering to the power supply lines.

Keith
 

keith1200rs said:
Have a look at the micro power supply lines. There is probably either a dip or huge spike when the contactor switches. You need to add some filtering to the power supply lines.

Keith
Click to expand...

Can you help me to add filtering to the power supply lines.
 

keith1200rs said:
Have a look at the micro power supply lines. There is probably either a dip or huge spike when the contactor switches. You need to add some filtering to the power supply lines.

Keith
Click to expand...

when contactor gets on electromagnetic induction and huge spike are produced in the wire .i have one doubt sir can watch dog timer will stop this issue ?
 

santoshaxl said:
when contactor gets on electromagnetic induction and huge spike are produced in the wire .i have one doubt sir can watch dog timer will stop this issue ?
Click to expand...

A watchdog timer would only reset the microcontroller, restarting the program. That's already the problem. ;)

Ken
 

Better option is to use two separate powersupplies one for micro and other for relay.

Dont forget the opto isolate the microcontroller output pin
 
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    larten

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I am using different power supplies, and I am also using optocoupler to switch Contactor.

If my perception is true, spikes will be generated due to back emf so, though we use different power supplys, the input supply for power supplies are common. So definetly we need some filtering circuit to eliminate spikes and back emf effects. If you are convenced with me then lets focus on filtering circuit which eliminates spikes and back emf effects.
 

"I am using different power supplies, and I am also using optocoupler to switch Contactor." "...though we use different power supplys, the input supply for power supplies are common."
By "input supply" are you referring to the mains side, or do you use one DC supply to feed a regulator for microcontroller and another regulator (or not) for the contactor? In this case the routing of grounds is very important in a mix of power systems like of this. All the ground connections in the microcontroller should be brought to one point. All of the ground connections on the contactor circuit should be brought to another point. These two points then should be wired directly to a single point in the power supply common. This is called a star system and is used to prevent "ground loops" that happen when high currents in the contactor common may generate voltage differentials along the microcontrollers common.

Can you post a schematic of your circuit?

Ken
 

You wiring details must be pretty screwed up if you are getting resets and already are using 2 power supplies and opto isolators!!! I would suspect some sort of ground loop. Is the ground return on power supply 1 connected to the ground return on power supply two? With the optoisolator drive, you do not need to have the two power supplies tied together in any way.

Failing that, get out the oscilloscope and look at the voltages on the microcontroller power supply and any input/reset pins. Make sure the scope probe is locally grounded to the microcontroller ground when doing this test. Add shunt capacitors or series inductors as needed to get any droops/spikes under control.

It is common practice to have a back diode and a small capacitor (like 1000 pf) across any relay coils to keep spikes locallized.
 

Dear, connect an RC circuit at the Output to contractor to minimise the spike from it
 

Isolate Power supplies

Battery 1

Analogue V
Analogue Gnd

Battery 2

Digital V
Digital Gnd
 

bikashh said:
Dear, connect an RC circuit at the Output to contractor to minimise the spike from it
Click to expand...

How to calculate RC network?

---------- Post added at 19:14 ---------- Previous post was at 19:09 ----------
biff44 said:
You wiring details must be pretty screwed up if you are getting resets and already are using 2 power supplies and opto isolators!!! I would suspect some sort of ground loop. Is the ground return on power supply 1 connected to the ground return on power supply two? With the optoisolator drive, you do not need to have the two power supplies tied together in any way.


It is common practice to have a back diode and a small capacitor (like 1000 pf) across any relay coils to keep spikes locallized.
Click to expand...


Yes, both power supplie sare powerd from common mains. I am using back diode accross relay coils of sugar cube relay to switch Contactor.
 

the contractor is AC driven or DC?, single phase or three phase?
 

try switch the contractor at zero crossing, it will reduce spike
 

Post your circuit, the problem seems to be odd.

It will be helpful if you post the exact circuit diagram of your work.
 

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