PIE 422Plus Diagnostic Thermocouple & Milliamp Calibrator

Ground Leak Detection

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 a 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 or where insulation has broken down. Turn on Ground Leak Detection and use the PIE 422Plus 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 422Plus display.

The PIE 422Plus 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.

Using Ground Leak Detection

The PIE 422Plus supplies a nominal 24 volts DC at 24 mA to the 2 Wire Transmitter or loop. The current passed by the transmitter will be accurately displayed by the PIE 422Plus along with an indication of leakage current on the display. If there is an uncontrolled loop, a transmitter with upscale burnout, bad or missing sensor or a short the display shows “OVER RANGE” and the red OVERLOAD LED will flash.

Note: Many installed transmitters will normally indicate 0.01 to 0.10 mA leakage without significant control problem. Unstable readings may indicate loose connections or the presence of moisture.

Typical Error Conditions

The PIE 422Plus is supplying the loop voltage. A calibrated transmitter is limiting the loop current to 12.00 mA. An additional 0.51 mA is not controlled by the transmitter and is leaking somewhere in the loop.

The PIE 422Plus is supplying the loop voltage. There is an control loop error. This may be a transmitter (set for upscale burnout) with a bad or missing sensor, or a short in the loop. The red ERROR LED will also flash.

Calibrate 2 Wire Transmitters

With LEAK DETECT enabled the 422Plus indicates when there is an ground fault in the loop or an internal problem with the transmitter allowing unregulated current to pass through causing offsets in the loop current.

Reading Thermocouple Sensors

READ

Choose this function to measure temperatures with a thermocouple probe or sensor.

Calibrating Thermocouple Instruments

SOURCE

Choose this function to provide a simulated thermocouple signal into controllers, temperature transmitters, indicators or any input devices that measure thermocouple sensors.

Connections

Simulating or reading thermocouples requires the use of thermocouple or extension grade thermocouple wire. Plug thermocouple wires into the miniature thermocouple jack or place bare thermocouple wires onto the brass block under the screws.

The PIE 422Plus has two banana jacks mounted in the top end of the housing. These are not temperature compensated and are to be used only for millivolt signals.