12226 Simpson, 12226 Datasheet - Page 13

• Manufacturer Part Number: 12226
• Description: Analog Multimeters 270-5 VOM HIGH A
• Manufacturer: Simpson

Specifications of 12226

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

4.12
d.
e.
f.
Some industries measure in terms of voltage or current ratios (decibels) based
on a specific reference level. The dB scale on the 270 serves this purpose and is
calibrated to a reference level (zero dB) or 0.001 watt into 600 ohms. The scale
calibration of -20 to +10 dB is for the 0-2.5V range (zero dB = 0.775V). Higher
ranges may be used by adding an appropriate dB value to the reading in accor-
dance with chart on the following page.
a.
b.
c.
c.
Do not use the 500V range for decibel
readings.
d.
Turn OFF power.
Connect the test leads across the cir-
cuit being measured with the black
test lead to the ground side.
Turn on power in the test circuit. Read
the output voltage on the appropri-
ate AC voltage scale. For the 0-2.5V
range, read the value directly on the
scale marked 2.5 VAC. For the 10V,
50V, or 250V ranges, use the red scale
marked AC and read the black fig-
ures immediately above the scale.
Decibel Measurement (-20 to +50 dB)
Review the safety precautions in
paragraph 4.1.
Set the functions switch at AC (figure
4-6).
Plug the black test lead into the -
COMMON jack and the red test lead
into the + jack.
Use operating instructions for AC
VOLTAGE MEASUREMENT, 0-2.5/
10/50/250/500V RANGES (para-
graph 4.9).
Read decibels on the bottom scale
marked dB. For the 10/50/250V
ranges, add the appropriate factor
from the following chart.
20
Figure 4-6. Jacks and Switch
Positions for Measuring Decibels
Figure 4-5. Jacks and Switch for
Output Measurement
COMMON
COMMON
COMMON
READ MANUAL BEFORE USE
READ MANUAL BEFORE USE
WARNING
WARNING
A.C.
A.C.
10V.
2.5V.
1V.
50V.
250V.
10V.
50V.
250V.
AMPS
2.5V.
IV.
AMPS
ALL TERMINALS IKV. MAX
ALL TERMINALS IKV. MAX
270
270
OUTPUT
350 VDC
MAX
4.
4.1
4.
5.
6.
This section contains information required to operate the 270-5 safely and prop-
erly.
Multifunction Instruments, (VOM’s), such as the 270-5 are intended as general
purpose measuring instruments for use in low power circuitry such as found in
consumer appliances, TV and radio receivers, and in general laboratory applica-
tions. Their use is not recommended in high voltage, high power circuitry where
operator errors and inadequate personal protective measures could result in
serious injury from arcing or explosion. Such circuitry is found in industrial or
commercial applications such as induction (r-f) heaters and broadcast transmit-
ters, power substations and distribution centers, x-ray equipment, large motor
controls, etc. Working in the high voltage section of such equipment requires
single-function, often specially designed, instruments operated by specially
trained personnel who use appropriate protective equipment and procedures.
The following precautions are commonly recognized safe practices to adopt and
specific hazards to avoid, and are not implied to be sufficient to safeguard un-
trained personnel in all circumstances. Neither is this manual a substitute for
technical manuals covering the equipment in which measurements are to be
made. Always refer to the equipment manual and its specific warnings and
instructions and observe them as well as those contained herein.
Zero Ohms:
Circuit Jacks:
Pointer Adjust:
for Zero:
OPERATION
Safety Precautions
Off/Transit Position: This function switch position opens
the 270 common and + jack inputs to avoid accidental
instrument overload or internal battery drain. It also
shunts the sensitive instrument during transit to pro-
vide damping during non-use periods.
This control is used to compensate for variation in the
voltage of internal batteries.
There are eight jacks on the front panel marked with
the functions they represent (Fig. 3-1). These jacks
provide electrical connections to the test leads. The
COMMON (-) jack is used (in conjunction with black
test lead) as the reference point for measurement of
all the functions with the exception of the 10A range.
(Refer to Section 5, Operator Servicing.)
With the Volt-Ohm-Milliammeter in an operating posi-
tion, check that the pointer indicates zero at the left
end of the scale when there is no input. If pointer is off
zero, adjust the screw located in cover below the cen-
ter of the dial. Use a small screwdriver to adjust the
screw until the pointer rests freely over the zero mark
at the left end of the scale. This procedure will avoid
disturbances to the zero setting by subsequent
changes in temperature, humidity, vibration, and other
environmental conditions.
13
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