Find hidden loop problems – Ground Leak Detected with Loop Diagnostics
Have you ever replaced a “faulty” transmitter only to find the problem was somewhere else in the loop? And did you end up throwing the transmitter away after you fixed the other problem “just in case” the transmitter was faulty?
If you find a loop where the transmitter is calibrated correctly but all the readings elsewhere in the loop have a fixed offset, this is due to Zero Shift. This zero shift is typically caused by some current in the loop bypassing the transmitter. This might be caused by ground faults, moisture or corrosion.
If you have some loops that are erratic after it rains, there may be moisture present in a junction box where insulation has broken down. Turn on Ground Leak Detection and use the PIE 334Plus to power up the loop. Any current that isn’t controlled by the transmitter or other current control element will be indicated as leakage on the PIE 334Plus display.
The PIE 334Plus powers up the 2-Wire transmitter or loop and indicates the total current and the uncontrolled current. This provides information useful in troubleshooting loop errors.
Typical Error Conditions
The PIE 334Plus is supplying the loop voltage. A calibrated transmitter is limiting the loop current to 12.00mA. An additional 0.51 mA is not controlled by the transmitter and is leaking somewhere in the loop. Click on the link Hidden loop problems found for more information on troubleshooting loops as well as a video demonstration of Loop Diagnostics in action.
The PIE 334Plus is supplying the loop voltage. There is a control loop error. This may be a transmitter (set for upscale burnout) with a bad or missing sensor, or a short in the loop