|
|
Subject - Quick find for short in a control system...
|
|
ejp
|
When I had to find a short in a 110VAC control system on a pallitizer that only had a single 2 amp control circuit fuse which would blow as soonas the power was turned on,there were little choices available to find the short.With dozens of relays,solonoids and wiring to and from limits and optic devices,I had to find a quick way to find the short.My idea was to replace the 2 amp fuse with a 200 watt incandesant light bulb ("ballast").Then I traced all the wiring for the 1.5 amp load of the bulb using a clamp meter.Since current flow in a series circuit is equal at all points of the circuit I knew that the short would be limited to the current drawn by the 200 watt bulb.It took only a minute to find the signature load and trace it to a solonoid valve coil that had shorted interally.By using a clamp (ammeter) to randomly check control wiring (all red)for the load of the 200 watt bulb, I did not have to check all of the components individually.
|
|
sled dog
| excellent idea for finding that short! that control system could probably use a few more fuses for those dozens of solenoids, though. its a good practice to fuse loads.
|
|
