UNI-T UT203R Digital Clamp Meter, True RMS, 400 A AC/DC, NCV

UNI-T UT203R Digital Clamp Meter, True RMS, 400 A AC/DC, NCV

The UNI-T UT203R is a digital True RMS clamp meter designed to measure AC and DC currents up to 400 A without disconnecting the conductor. It also measures AC/DC voltage, resistance, capacitance and frequency, and provides diode testing and continuity checking. Non-contact voltage detection (NCV), automatic ranging and a backlit display make it suitable for electrical installation testing, equipment maintenance and troubleshooting.

Key specifications: AC/DC current up to 400 A • True RMS • AC/DC voltage up to 600 V • 40 MΩ • 40 mF • 10 MHz • NCV • CAT III 300 V / CAT II 600 V

Key Features and Benefits

• 400 A AC/DC clamp measurement – measures alternating and direct current without opening the electrical circuit.
• True RMS technology – provides effective-value measurements of AC signals, including non-sinusoidal waveforms, within the specified frequency range.
• Non-contact voltage detection (NCV) – detects AC electric fields near cables and outlets, with two selectable sensitivity levels (EFLo / EFHI), audible indication and a flashing LED.
• Multifunction measurement – combines current and voltage measurement with resistance, capacitance up to 40 mF, frequency up to 10 MHz, diode and continuity testing.
• Automatic ranging – automatically selects the appropriate measurement range, simplifying operation.
• REL measurement mode – enables relative measurements, reference-value subtraction and zero adjustment before DC current measurements.
• MAX/MIN and HOLD functions – record maximum and minimum readings and freeze displayed values.
• Backlit LCD – provides up to 4099 display counts for convenient measurement reading.
• Automatic power-off and warnings – features automatic shutdown after approximately 15 minutes of inactivity, low-battery indication and overload warnings.

Applications

The UNI-T UT203R is suitable for:

• Testing electrical installations in residential and commercial buildings.
• Measuring current in electrical equipment, motors and power supply circuits.
• Troubleshooting DC electrical systems, including automotive applications.
• Testing resistors, capacitors, diodes and circuit continuity.
• Checking voltage presence and measuring electrical signal frequency.

It is intended for general electrical testing and maintenance by DIY users, electricians and technical personnel, provided that the measurement conditions comply with the instrument's safety ratings.

Compatibility and Limitations

• Clamp measurements are performed on a single conductor. Enclosing both live and neutral conductors may cause magnetic field cancellation and incorrect readings.
• Maximum conductor diameter: 28 mm.
• True RMS current and voltage frequency response: 45–400 Hz.
• DC current measurement requires zero adjustment using the REL function for accurate readings.
• NCV detects AC electric fields and must not be used as the sole method of confirming that a circuit is de-energized.
• The UT203R does not measure temperature. Temperature measurement is available on the UT204R model.
• The meter is not designed for insulation resistance testing or electrical power quality analysis.

Technical Specifications

Parameter	Specification
Model	UNI-T UT203R
Instrument type	Digital AC/DC clamp meter
Measurement technology	True RMS
Range selection	Automatic
Current Measurement
AC current ranges	40.00 A / 400.0 A
DC current ranges	40.00 A / 400.0 A
Current resolution	0.01 A / 0.1 A
AC/DC current accuracy	±(2% + 5 digits)
Guaranteed current accuracy range	5–100% of selected range
AC current frequency response	45–400 Hz
Current overload warning	410 A
Voltage Measurement
DC voltage ranges	400.0 mV / 4.000 V / 40.00 V / 400.0 V / 600 V
DC voltage resolution	0.1 mV / 0.001 V / 0.01 V / 0.1 V / 1 V
DC voltage accuracy, 400 mV	±(0.7% + 3 digits)
DC voltage accuracy, other ranges	±(0.5% + 2 digits)
AC voltage ranges	4.000 V / 40.00 V / 400.0 V / 600 V
AC voltage resolution	0.001 V / 0.01 V / 0.1 V / 1 V
AC voltage accuracy, 4 V and 40 V	±(1.0% + 5 digits)
AC voltage accuracy, 400 V and 600 V	±(0.8% + 5 digits)
True RMS AC voltage frequency response	45–400 Hz
Voltage input impedance	Approximately 10 MΩ
Resistance Measurement
Resistance ranges	400.0 Ω / 4.000 kΩ / 40.00 kΩ / 400.0 kΩ / 4.000 MΩ / 40.00 MΩ
Resistance resolution	0.1 Ω / 0.001 kΩ / 0.01 kΩ / 0.1 kΩ / 0.001 MΩ / 0.01 MΩ
Accuracy, 400 Ω and 4 kΩ	±(1.0% + 2 digits)
Accuracy, 40 kΩ and 400 kΩ	±(0.8% + 2 digits)
Accuracy, 4 MΩ and 40 MΩ	±(2.5% + 5 digits)
Capacitance Measurement
Capacitance ranges	40.00 nF / 400.0 nF / 4.000 µF / 40.00 µF / 400.0 µF / 4.000 mF / 40.00 mF
Capacitance resolution	0.01 nF / 0.1 nF / 0.001 µF / 0.01 µF / 0.1 µF / 0.001 mF / 0.01 mF
Accuracy, ranges up to 4 mF	±(4% + 5 digits)
Accuracy, 40 mF range	±10%
Frequency and Additional Functions
Frequency measurement via input terminals	10 Hz–10 MHz
Frequency accuracy	±(0.1% + 4 digits)
Frequency measurement in AC voltage mode	10 Hz–60 kHz
Accuracy in AC voltage frequency mode	±(0.5% + 2 digits)
Duty cycle measurement	Yes, square-wave signals up to 10 kHz
Diode test	4.000 V range, 0.001 V resolution
Audible continuity	Continuous buzzer at ≤10 Ω
Non-contact voltage detection	NCV, EFLo / EFHI
General Specifications
LCD display counts	Up to 4099 (4000-count class)
Display dimensions	37 × 25 mm
Display refresh rate	Approximately 3 readings/s
LCD backlight	Yes
HOLD / MAX / MIN / REL	Yes
Automatic power-off	Approximately 15 min., can be disabled
Power supply	2 × 1.5 V AAA (R03)
Maximum jaw opening	28 mm
Dimensions	215 × 63.5 × 36 mm
Weight	Approximately 235 g including batteries
Operating temperature	0–50 °C, subject to humidity limitations
Storage temperature	−20 to +60 °C
Maximum operating altitude	2000 m
Drop protection	1 m
Safety rating	CAT II 600 V / CAT III 300 V
Insulation	Double or reinforced insulation
Standards	EN 61010-1, EN 61010-2-032, EN 61010-2-033, EN 61326-1

Accuracy notes: Accuracy is expressed as ±(% of reading + digits). The specified accuracy conditions are 23 ± 5 °C and relative humidity ≤80%. Additional measurement error may apply to non-sinusoidal signals depending on their crest factor.

Design and Controls

The meter features spring-operated clamp jaws, a rotary function selector, a backlit LCD and dedicated function buttons.

Two input terminals are provided for voltage, resistance, capacitance, frequency and diode measurements. Current is measured with the clamp jaws rather than test leads.

The NCV sensor is located at the upper end of the housing and provides visual and audible AC electric field indication.

Important Safety and Operating Notes

• Do not exceed the 600 V voltage measurement limit or the CAT II 600 V / CAT III 300 V safety ratings.
• Enclose only one conductor when measuring current and keep it centered inside the jaws whenever possible.
• Disconnect circuit power and fully discharge capacitors before testing resistance, capacitance, diodes or continuity.
• Do not leave test leads connected to the meter when measuring current with the clamp.
• Inspect the meter and test leads before use and verify correct operation.
• Absence of an NCV indication does not confirm that a conductor is de-energized.

Package Contents

• UNI-T UT203R digital clamp meter – 1 pc.
• Test leads – 1 pair.
• Fabric carrying pouch – 1 pc.