A Digital Clamp Meter (DCM), or Clamp Multimeter, is an electrical test tool that combines a basic digital multimeter with a current sensor. Its primary advantage is the ability to measure AC (and sometimes DC) current without breaking the circuit, using a hinged "clamp" jaw.
Selector Switch Functions:
- OFF:
Powers off the meter.
- 20A~:
AC Current measurement mode (20 Amp range).
- 200A~:
AC Current measurement mode (200 Amp range).
- 600A~:
AC Current measurement mode (600 Amp range).
- 600V==:
DC Voltage measurement mode (600 Volt range).
- 2000Ω:
Resistance measurement mode (2000 Ohm range).
- 200KΩ:
Resistance measurement mode (200 Kiloohm range).
Input Jacks:
- COM:
Common (Ground) terminal. The black test lead is always plugged in here.
- V/Ω++:
Terminal for Voltage (V) and Resistance (Ω) measurements. The red test
lead is plugged in here for these measurements.
- Note:
The "++" symbol is non-standard and might be a printing error
or a brand-specific indicator, but its function is clear from context.
Safety Rating:
- CAT
III: Category III rating. This signifies the meter is designed to
withstand voltage transients (spikes) found in equipment at the
distribution level in buildings, such as distribution panels, circuit
breakers, and industrial equipment. It is a common and important safety
rating for automotive and mains electrical diagnostics.
- Voltage
Measurement (DC):
- Setting: Rotate
the selector to the 600V== position.
- Connections: Red
lead in V/Ω jack, Black lead in COM jack.
- Procedure: Connect
the probes in parallel with the circuit/component under test (e.g.,
across battery terminals).
- Resistance
Measurement (Ω):
- Setting: Rotate
the selector to the 2000Ω or 200KΩ position,
depending on the expected resistance value.
- Connections: Red
lead in V/Ω jack, Black lead in COM jack.
- Procedure: Ensure
the circuit is de-energized (no power). Connect the probes across the
component being tested.
- AC
Current Measurement (A~):
- Warning: Current
is measured in series with the circuit. Incorrect use can lead to a short
circuit.
- Setting: Rotate
the selector to the appropriate AC current range (20A~, 200A~,
or 600A~).
- Connections:
- For
the 20A~ range: Move the red test lead to the 20A jack.
- For
the 200A~ or 600A~ ranges: Move the red test lead to
the 200A/600A jack (the jack is likely a single port labeled
for both high-current ranges).
- Procedure: De-energize
the circuit. Break the current path and connect the meter in series so
the current flows through the meter. Re-energize the
circuit to take the reading.