Controls Transformer Circuit Breaker Tripping....

[alliedtech12887]

Ive got a 90VA panel transformer that is tripping very inconsistently, Ive installed another 100VA transformer and separated the controller power and the field device power. I've rung the wiring and also made sure there were no direct shots to ground or between the legs on the transformers. There is no rime or reason as to when this thing trips, my next step was going to be to install small in line circuit breakers on the outputs of any load carrying devices. I've used the tattle tales in the past for safeties but not sure if they'd work in this situation. Anyone have any input?

[chesehd]

Intermittent faults are the worst!

Give the tattletales a shot. At the very least it could help you define which output/circuit is the problem child.

If you have successfully separated the power between the control board and devices can you run a trend on when your outputs cycle and when the circuit breaker trips? If you have a spare input maybe you could wire in a relay directly to the transformer and use a spare input to monitor for when the state changes. Run your trends and check for when your outputs change and when that relay changes state.

It's kind of a long way around but it might help.

If that doesn't pan out and you are able to use the tattletales to identify which circuit is the issue check for what may be getting wet from condensation or a leaky valve body.

Good luck!

[Cool breeze 38]

inline fuses. low amp ones. Or turn one field device at a time and amp it out.
The way I read your post the field device transformer is tripping?

[crab master]

Have you measured the amperage?

Have you measured incoming voltage to the transformer? Outgoing voltage from? Voltage at all devices on the transformer?

Have you done a load calc on the devices that are on the secondary side of the power supply?

[joey791]

Now that you have separated the power is it still tripping? Have you fired off each output one by one to see if it trips on a certain output? I had one job that ate my lunch one time, installed by someone else, worked on by about 10 different companies and I had to repair in place, even chiller start/stops were wired wrong. Anyway there was a York centrifugal that everytime it started it would knock the controller offline for a second and cut off random outputs and lock them. Long story short, I was only given a few hours to troubleshoot everytime I went out there by the customer(not a contract), come to find out the controls contractor had put a ct on the York chiller that was rated for nameplate running amps, not the spike at start, everytime it started the first time it send 15+volts to the inputs and would wreck my controller.