How to use a clamp meter for faster three-phase energy measurements

Up to 50% faster completion of three-phase voltage and current measurements*

The Fluke 377 FC and 378 FC clamp meters were the first handheld clamp meters with Fieldsense™ technology to measure voltage and current simultaneously using jaws. This means that these clamp meters can be used to perform continuous line-to-ground measurements and current measurements, resulting in calculated wire-to-line voltage measurements and phase rotation information. These measurements indicate whether the three-phase system is working as intended.

Relative phase measurements are simplified

L1, L2, and L3 (or Line 1, Line 2, and Line 3) are common naming conventions for wires in three-phase alternating current (AC) systems. On three-phase loads, voltage and current need to be measured sequentially using wires.

The current Select-Measure-Write, Select-Measure-Write workflow is time-consuming. It requires you to repeat these steps for all three phases. In addition, a third person or additional person is required to help connect the two wires and clip them to the wires when the values are written.

The Fluke 377 FC and 378 FC revolutionize voltage and current measurement in three-phase power systems. Instead of using test leads to make each measurement individually and perform manual calculations, you now only need to take three measurements with a clamp meter. The clamp meter then automatically calculates the entire set of relative phase voltages based on the relative measurements. These clamp meters are equipped with a dual display that measures and displays voltage and current simultaneously.

How to use a clamp meter for faster three-phase energy measurements

How to make a three-phase measurement

Set up

Turn the control knob to the FieldSense icon (Fieldsense™)

Use the grounding wire to connect the clamp gauge to the ground terminal

Press and hold MIN MAX (min, max) for 2 seconds. The clamp meter is now in wire-to-wire mode with L1-L2-L3 on the display.

Test

Slip the jaws onto the first wire. Wait for the measurements on the screen to stabilize. The screen will turn green, beep, and display L1.

Move the jaws to the second wire in 10 seconds. Wait for the measurements on the screen to stabilize. You will hear a beep and L2 will appear on the screen.

Move the jaws to the last wire in 10 seconds. Wait for the measurements on the screen to stabilize. You will hear a beep and L3 will appear on your screen.

compute

Once the L1-L2-L3 measurements are complete, the total voltage between each pair of wires is calculated using a clamp meter:

Press MIN MAX (minimum maximum value) once: The screen displays the total voltage between L1 and L2.

Press MIN MAX again: The screen shows the total voltage between L2 and L3.

PRESS MIN MAX FOR THE THIRD TIME: THE SCREEN DISPLAYS THE TOTAL VOLTAGE BETWEEN L3 AND L1.

When in line-to-line mode, you can view each line-to-ground measurement:

Press MIN MAX again to display the L1 measurement.

Press MIN MAX again to display the L2 measurement.

Press MIN MAX again to display the L3 measurement.

To view the L1-L2-L3 measurements, continue to press the "MIN MAX" button and scroll through the measurements.

To exit wire-to-wire mode, press and hold the MIN MAX button for about 2 seconds.

Phase sequence indication function

When dealing with three-phase equipment, one of the biggest needs is knowing the correct phase sequence and then ensuring that the work is done in the correct order during installation, maintenance, and troubleshooting. In addition to simplifying the measurement process, the Fluke 377 FC and 378 FC automatically calculate the phase rotation. All you need to do is take all three three-phase measurements when connected to the Fluke Connect (FC) app, and the phase sequence is automatically calculated and displayed on the FC app.

apply

Installation of HVAC motors and compressors

Determine if the load is balanced for each phase during installation and if the phase rotation is correct. Unbalanced three-phase systems can lead to poor motor performance or premature failure, resulting in costly downtime. Imbalances can occur at any point in the distribution system. The load should be distributed evenly between each phase of the input feeder circuit. Motors or compressors powered by an unbalanced system will run at higher temperatures and will eventually fail prematurely.

Troubleshoot three-phase motors

Determines when a fuse is blown in a certain phase, resulting in a phase break. In the case of a phase outage, the other two phases will draw more current, overheating the windings of the pump, motor, or compressor. By measuring the phase of the incoming line voltage, the user can determine which phase is faulty and help prevent damage to the device. If a phase outage occurs while the equipment is running, it will start to overheat due to the increased load on other phases. If the device has stopped, the device will restart only after the fuse has been replaced and all three phases are present again.

*β tests conducted at the customer's site showed a 50% reduction in the time required for three-phase measurements.

How to use a clamp meter for faster three-phase energy measurements

Sections viewed

Contact

working hours