12227 Simpson, 12227 Datasheet - Page 15

• Manufacturer Part Number: 12227
• Description: Analog Multimeters 270-5RT VOM HI A
• Manufacturer: Simpson

Specifications of 12227

• Accuracy: +/- 1.75 %
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

4.10
0-1000V Range
e.
f.
g.
Turn off power to the circuit and wait until
the meter indicates zero before discon-
necting the test leads.
Use extreme care when working in high voltage circuits. Do not handle the
Instrument or test leads while the circuit being measured is energized. OB-
SERVE ALL SAFETY PRECAUTIONS in paragraph 4.1 and in the instruction
manual for the equipment being tested.
Do not attempt any circuit-to-ground voltage measurement which may exceed
1000 volts.
Be sure that the range switch is set to the 500V/1000V range, function switch to
AC position, and test leads connected to common and 1000V jack.
Do not touch the Instrument or test leads while the power is on in the circuit being
measured.
a.
b.
c.
d.
e.
f.
g.
Connect the test leads across the cir-
cuit voltage to be measured with the
black lead to the grounded side.
Turn on power.
For the 2.5V range, read the value
directly on the scale marked 2.5 VAC.
For the 10V, 50V, and 250V ranges,
read the red scale marked AC and
use the black figure immediately
above the scale. For the 500V range,
read the red scale marked AC and
use the 0-50 figures. Multiply the
reading by 10.
AC Voltage Measurement
Set the function switch at AC (Figure 4-3).
Set the range switch at 500/1000V position.
Plug the black test lead into the - COMMON jack and the red test lead in the
1000V jack.
Check that the power is off in the circuit being measured and that all its
capacitors have been discharged.
Connect the test leads across the circuit voltage to be measured with the
black lead to the grounded side, if any.
Turn on the power in the circuit being measured.
Read the voltage on the red scale marked AC. Use the 0-10 figures and
multiply by 100.
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18
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Figure 4-3. Jacks and Switch
Positions for measuring AC
Voltages
COMMON
COMMON
READ MANUAL BEFORE USE
WARNING
A.C.
10V.
2.5V.
1V.
50V.
250V.
500V.
1000V
AMPS
ALL TERMINALS IKV. MAX
270
A.C.
1000V.
D.C.
4.3
4.4
4.5
4.6
circuit power. When making measurements on the 50µA/250mV, 1 volt, or 10 amp
range, polarity can be corrected only by interchanging the test lead connector to
the current.
If the approximate voltage or current to be measured is known then the correct
range may easily be selected. However, particularly when working on faulty
equipment, the voltage or current is sometimes unknown or much higher than
normal and anticipated. When working on unfamiliar or unknown equipment,
always begin a measurement using the highest range available on the Instru-
ment. Once it is determined that the voltage is within the limits of a lower range,
change to the lower range.
Test leads are provided with accessory screw-on alligator clips which may be
attached to the probe tips. Eliminating the need to hand-hold test prods to a
circuit for extended periods, the test clips also reduce hand proximity to a high
voltage circuit while energized. Circuit power must, of course, be turned off and
any charged capacitors discharged before connecting or disconnecting clips to
or from the circuit.
NOTE:
Before measuring voltage review the SAFETY PRECAUTIONS listed in para-
graph 4.1. Also, when using the 270 as a millivoltmeter, care must be taken to
prevent damage to the indicating instrument from excessive voltage. Before
using the 250 millivolt range, use the 1.0-volt DC range to determine that the
voltage measured is not greater than 250 millivolts (or .25 volt DC).
a.
b.
c.
d.
e.
a.
b.
c.
d.
e.
Measurement Of Unknown Voltage Or Current
Test Leads
DC Voltage Measurement 0-250 mV Range
Set the function switch at +DC (Figure 4-1).
Plug the black test lead in the - COMMON jack and the red test lead into the
+50 µA/250mV jack.
Set the range switch at 50 µA COMMON position with 50V.
Connect the black test lead to the negative side of the circuit being measured
and the red test lead to the positive side of the circuit.
Read the voltage on the black scale marked DC and use the figures marked
0-250. Read directly in millivolts.
DC Voltage Measurement 0-1V Range
Set the function switch at + DC (Figure 4-1).
Plug the black test lead into the - COMMON jack and the red test lead into the
+ 1V jack.
Set the range switch at 1V (COMMON position with 2.5V).
Connect the black test lead to the negative side of the circuit being measured
and the red test lead to the positive side of the circuit.
Read the voltage on the black scale marked DC and use the figures marked
For polarity reversing see paragraph 4.2.
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