Analogue input cards being damaged
Analogue input cards being damaged
(OP)
I have a problem with a siemens analogue input card sustaining damage. Thermocouple from an injection mould is connected to the AI card. The TCs are in close proximity to the 230v heater wires in same wireway in mould. Faults on heaters sometimes transfer to TC and TC cables carry a surge or spike into the AI card which blows it. Question. Is there any recommended interface that can be put between thermocouple and analogue input card?
I can also be contacted at crowther.steven@gmail.com
I can also be contacted at crowther.steven@gmail.com





RE: Analogue input cards being damaged
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If we learn from our mistakes I'm getting a great education!
RE: Analogue input cards being damaged
If the thermocouple input is referenced to ground you could use a back to back diode on each wire to ground, The thermocouple voltage is too low to bias the diodes but the accidental AC from the heater would. A potted bridge would accomplish this if you connect each or the thermocouple module terminals to one of the AC terminals and ground the + & - terminals
Hope this helps
Roy
RE: Analogue input cards being damaged
Thanks again for your assistance.
RE: Analogue input cards being damaged
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Note the surge protection devices.
Or:
http:
Keith Cress
kcress - http://www.flaminsystems.com
RE: Analogue input cards being damaged
regards
Steven