The handheld digital phase volt-ampere meter is a purpose-built, portable dual-channel measuring instrument specifically engineered for in-situ diagnostics of voltage, current, and phase relationships. With its capacity to measure inter-voltage (U-U), inter-current (I-I), and voltage-current (U-I) phase angles, the device is an indispensable tool for identifying inductive or capacitive circuits, discerning three-phase voltage phase sequences, verifying transformer vector groups, and inspecting secondary circuits and bus differential protection systems. Furthermore, it aids in examining the wiring of energy meters and verifying the phase alignment of various current transformers (CTs) within differential protection configurations. Through clamp-type current transformer (CT) input, current measurements are conducted without the need to disrupt circuit continuity. Additionally, full galvanic isolation between input channels precludes the risk of short-circuiting due to accidental cross-wiring.

I. Operating Instructions for the Digital Phase Volt-Ampere Meter

Powering On and Function Selection

Begin by pressing the ON-OFF button to power up the instrument. Rotate the multifunction selector switch to choose the appropriate parameter and range setting.

1. Measuring AC Voltage

To measure alternating voltage, turn the selector switch to the 500V range corresponding to the U1 parameter. Insert the voltage probe into the U1 input terminal. For voltages below 200V, switch to the 200V range under U1 to enhance measurement precision.
Alternatively, U2 input terminals may be used with corresponding selector adjustments for voltage measurement.

2. Measuring AC Current

To measure alternating current, turn the selector switch to the 10A range aligned with parameter I1. Connect the secondary lead of clamp CT labeled “1#” to the I1 input terminal. Clamp the jaws onto the target conductor. If current is below 2A, shift to the 2A range for improved resolution.
Similarly, measurements can be conducted via the I2 input using clamp CT “2#” and the corresponding switch position.

3. Measuring Phase Angle Between Two Voltages

To assess the phase displacement between U1 and U2, set the selector switch to U1U2. During measurement, rotate clockwise to any of U1's ranges to view U1 voltage, or counter-clockwise to U2 ranges for U2 voltage, facilitating a dynamic view of input states.

4. Measuring Phase Angle Between Two Currents

When evaluating whether I2 lags behind I1, adjust the switch to I1I2. Measurements can be taken by rotating the selector toward either I1 or I2 positions to confirm respective input values, enabling comprehensive phase relationship analysis.

5. Measuring Phase Angle Between Voltage and Current

To determine the phase angle between voltage and current:

• Input voltage through U1 and current via I2 using clamp CT “2#”, then set the switch to U1I2. This yields the lag angle of current relative to voltage.

• Alternatively, input voltage via U2 and current through I1 using clamp CT “1#”, setting the switch to I1U2 to observe voltage lagging behind current.

Dynamic rotation of the selector switch allows instant toggling between voltage and current ranges for comparative accuracy.

6. Phase Sequence Identification in Three-Phase Three-Wire Systems

Set the selector switch to U1U2. Connect phase U to U1, phase V to both ± terminals of U1 and U2, and phase W to U2. If the measured phase angle is approximately 300°, the system is in positive phase sequence; a 60° reading indicates negative phase sequence.

Alternatively, connect U to U1, V to both U1 and U2, and W to ± terminals of U2. A 120° phase difference denotes positive sequence, while 240° indicates negative sequence.

7. Phase Sequence Identification in Three-Phase Four-Wire Systems

Position the selector on U1U2. Connect phase U to U1, phase V to U2, and the neutral line to the ± terminals of both inputs. A measured phase angle of roughly 120° corresponds to positive sequence; around 240° indicates negative sequence.

II. Precautions for Using the Digital Phase Volt-Ampere Meter

1. Identification of Polarity Terminals
   Voltage input ports marked with red lines denote the "same-name" terminal. Clamp CTs feature a red “I” marking to indicate the identical polarity end.

2. Safe Handling of Test Leads
   Do not insert or remove voltage/current test cables from the housing when voltage is already applied to the input terminals. Avoid touching the input connector surfaces during operation to prevent electric shock.

3. Voltage Input Limitations
   Never measure voltages exceeding 500V to avoid damage or hazard.

4. Instrument Integrity
   Do not operate the device if the rear cover is not securely fastened.

5. Internal Circuit Integrity
   Unauthorized alterations, modifications, or recalibration of internal circuitry are strictly prohibited to ensure measurement accuracy and operator safety.

This phase volt-ampere meter offers a robust, field-oriented solution for engineers and technicians requiring accurate, safe, and multi-functional power diagnostics. Its dual-channel, non-invasive design, and advanced phase analysis capabilities make it essential in the modern power systems toolbox.