0
\$\begingroup\$

I found this component connected in parallel with an inductive load ( three phase coil used to disengage a mechanism ) the load keeps heating and burning after a while ( had to rewind it ) and no fuses burn or circuit breaker trip ,can this component be the reason? how can I test it?

enter image description here

schematic

simulate this circuit – Schematic created using CircuitLab

The data sheet ( if it's the right one ) says it's an RC circuit with 0.22uf+220ohm. R101 datasheet The supply voltage is 380v three phases , the load and this component are connected in parallel. The load is 3 sets of two in series coils , where the sets are connected in star connection.

\$\endgroup\$
  • 1
    \$\begingroup\$ Please provide some context so that this question becomes helpful for a broader audience. A schematic showing the RC circuit together with the supply and the load would be a start. Otherwise, people will start to suggest that your question be closed because it is too specific. Repair or troubleshooting questions can be asked such that they are interesting for other people as well. Remember that others want to learn from your problem, too; this is the motivation of this site. However, a hint: Does your load still become too hot with the RC device disconnected? Does this test teach us something? \$\endgroup\$ – zebonaut Jul 16 '18 at 7:48
  • \$\begingroup\$ @zebonaut I edited the post but I can't add a schematic on android now, and I didn't test the load without the unit cause who nows what can happen ? \$\endgroup\$ – Chebhou Jul 16 '18 at 8:51
  • \$\begingroup\$ This snubber seems highly unlikely to be the problem. \$\endgroup\$ – Brian Drummond Jul 16 '18 at 9:08
  • 2
    \$\begingroup\$ I see some issues. You quote a data sheet (Link? Maybe someone who wants to help would like to read it, too - without having to search the entire internet?) saying it's an RC unit, but in the blurry picture, I find inductors (L) and resistors (R) - no capacitors (C). Then - if the snubber has in internal short, it would be the one to get hot (not the load). If it's open, it's already removed from the circuit anyway. You don't need to test the load, but you could tell us more about the device. "who knows what can happen?" We certainly can't, with the little pieces of information you told us. \$\endgroup\$ – zebonaut Jul 16 '18 at 9:20
  • 1
    \$\begingroup\$ ... and you can always hand-draw a schematic and post a readable picture? \$\endgroup\$ – zebonaut Jul 16 '18 at 9:22
1
\$\begingroup\$

Assuming this is an RC snubber, it is intended to suppress the voltage spike that would be generated across the inductive load when it is disconnected. It seems unlikely that a failure would cause it to become an open circuit without evidence of burning. However if it has failed in that manner, it is no longer suppressing voltage spikes and that may have caused some shorted turns leading to the coil failure described.

It could also be that the RC was never sufficient to suppress transients sufficiently to prevent long term deterioration and that is what has happened.

An oscilloscope could tell you the magnitude of the voltage spike that occurs when the coil is turned off. Connecting and disconnecting the RC would let you see the spike with and without the RC. Since you have rewound the coils, you should be able to determine what level of voltage the windings should be able to withstand. If you can determine the age and duty cycle of the coils, you would have some idea of the quality of the original design. Knowledge of anything that has changed in the use or connection of the coils might provide some useful insight.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.