Urrea UD77, User Manual And Warranty

Page: 17 / 24

E N G L I S H
17
4. Connect the test leads to the circuit to
be tested.
5. Reapply power to the circuit, the
measured voltage will appear on the
display of the instrument.
6. If the red test lead is connected to the
negative (or lower voltage) side of the
circuit, a minus sign will appear on the
display, at the left side.
7. Disconnect power to the circuit before
removing the test leads from the circuit.
Three-Phase AC Volts:
This Meter is designed to primarily measure
household AC voltage. When measuring
THREE-PHASE circuits line-to-line, the value
of the voltage is actually higher than the
rated line-to-ground 3-phase voltage.
It is very important that you do not exceed
the maximum AC (RMS) rating of this
Meter, which is 750V AC. To find the RMS
voltage line-to-line on a 3-phase power line,
multiply the rated line-to-ground voltage by
the square root of 3 (approx. 1.732).
For example, if you connect this Meter to
a 480 Volts 3-phase line (i.e. 480 V line-to-
ground), the total available line-to-line
voltage is about 832 V AC ( 480 V x 1.732).
Severe damage and a dangerous shock
hazard could result because this exceeds the
rating of this Meter.
4.2 Measuring resistance measuring
(resistance, continuity).
CAUTION: TURN-OFF POWER AND
DISCHARGE ALL CAPACITORS ON CIRCUIT TO
BE TESTED BEFORE ATTEMPTING IN-CIRCUIT
RESISTANCE MEASUREMENTS. FAILURE TO
DO SO MAY END UP IN EQUIPMENT (AND/
OR INTRUMENT) DAMAGE. THE RESISTANCE
MEASURING CIRCUIT APPLIES A KNOWN
VALUE OF CONSTANT CURRENT THROUGH
THE UNKNOWN RESISTANCE AND THEN
MEASURES THE VOLTAGE DEVELOPED
ACROSS IT. THEREFORE, REMOVE ALL
POWER TO THE CIRCUIT UNDER TEST WHEN
MAKING RESISTANCE MEASUREMENT. IF
ANY VOLTAGE IS PRESENT IN THE TEST
CIRCUIT, AN ERRONEOUS READING WILL
RESULT. THIS METER MAY BE DAMAGED
IF VOLTAGE GREATER THAN 600 V AC IS
PRESENT.
NOTE: When measuring critically low
resistance values, touch tips of test
leads together and record the reading.
Subtract this reading from an additional
measurement to obtain the most accurate
value.
• When measuring large resistances, reading
may be unstable due to environmentally
induced electrical noise. In this case,
directly connect the resistor to input
terminals of the Meter or shield the resistor
at potential of the COM input terminal to
obtain stable reading.
For resistance above 1 MΩ, the display
might take a few seconds to stabilize. This
is normal for high-resistance readings.
• The Meter has a circuit to protect the
resistance range from over-voltage (600V
AC). However, to prevent accidentally
exceeding the protection circuit’s rating