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9 years, 12 months ago.
Mbed crashing due to Inductive loads
I am using Mbed to control some relays which in turn control the contactors. The mbed seems to be working perfectly and completing all processes. But whenever the contactor coil is open and its coil discharges the Mbed tends to crash. I placed a freewheeling diode across the contactor coil this avoided the mbed to crash but I did notice mbed would freeze for a second or two. I have tried to power contactors with a different supply still I see the Mbed freezing. I also noticed that when I powered contactors independently the Mbed would freeze even after complete electrical isolation. The mbed is placed close to contactors though.
I would be very grateful if someone could explain what I can do to avoid this situation.
1 Answer
9 years, 12 months ago.
1. Free-wheeling diode across relay coil too. 2. Opto-Iisolate the mbed from the power-ckt. 3. Use a A.C. line Filter in the Contactor Power-Supply.
thanks so much Pramod. Can you tel me how I can calculate the values for the line filter.
posted by 20 May 2014I am using different sources to power the Mbed and the Contactor. Mbed still freezes when i remove power from the coil. I bought the relay board which comprises of the free wheel diodes. I have attached the link to the relay board. http://www.sainsmart.com/arduino-compatibles-1/relay/16-channel-12v-relay-module-for-pic-arm-avr-dsp-arduino-msp430-ttl-logic.html
posted by 20 May 2014
Line Filters are available in the market, see Schaffner FN2030-16-06 as an example. The mbed-Ground and Relay-Ground should be seperate, by using an opto-isolator.
posted by Pramod Joglekar 21 May 2014