12227 Simpson, 12227 Datasheet - Page 12

• 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

3.
3.1
The front panel controls, jacks and indicators are described in Table 3-1 and illus-
trated in Figure 3-1.
1.
2.
3.
All operating and adjustment controls, jacks and indicators for the Simpson 270-
5 are described in this section. Become familiar with each item before operating
the Instrument.
CONTROLS, JACKS AND INDICATORS
Front Panel Description
Front Panel:
Range Switch:
Function Switch:
Figure 3-1. Controls, Indicators and Connector
Table 3-1. Controls, Jacks and Indicators
COMMON
COMMON
READ MANUAL BEFORE USE
WARNING
A.C.
10V.
2.5V.
1V.
50V.
250V.
500V.
1000V
AMPS
The 270-5 Volt-Ohm-Milliammeter is a large, easy-to-
read 4-1/4” indicating Instrument. Switch positions
and circuit jacks are marked in white characters for
easy reading.
The range switch may be rotated in either direction to
select the desired voltage, current, or resistance range
position.
The function switch has four positions: Off/Transit, +DC,
-DC and AC. To measure DC current or voltage, set
the function switch at the -DC or +DC position, de-
pending on polarity of the signal applied across test
leads. To measure AC voltage set the function switch
to the AC position. For resistance measurement, the
switch may be set in either the +DC or -DC position.
The polarity of the internal ohmmeter battery voltage
at the (+) positive jack is identical to the function switch
polarity setting and opposite at the (-) common jack.
ALL TERMINALS IKV. MAX
270
12
A.C.
1000V.
D.C.
4.13
4.14
4.15
Range
NOTE: The maximum voltage ratio that can be measured is +50 dB on the 0-250V
range.
e.
a.
b.
c.
d.
e.
a.
b.
c.
d.
e.
f.
g.
h.
NOTE: For polarity reversing see paragraph 4.2.
a.
b.
0
0
0
0
V
2 -
1 -
5 -
2 -
O
L
5 .
0
0
5
If dB measurement is being made to a 0.0006 watt into 500 ohm reference
level, subtract +7 dB from the reading obtained on the 270-5.
Direct Current Measurement
Do not change the setting of the range or change the function switches while
circuit under measurement is energized.
Never disconnect test leads from circuit under measurement while the circuit
is energized.
Always turn the circuit power off and discharge all the capacitors before
setting the switches or disconnecting the leads.
Never exceed the circuit-to-ground voltage of the instrument (1000V MAX.,
Table 1-1, Item 16).
Always connect the Instrument in series with the ground side of the circuit.
Direct Current Measurement 0-50 µA Range
Set the function switch at + DC.
Plug the black test lead into the - COMMON jack and the red test lead into the
+50µA/250mV jack.
Set the range switch at 50µA (dual position with 50V).
Turn OFF power. Then discharge any capacitors in the circuit.
Open the ground side of the circuit in which the current is being measured.
Connect the VOM in series with the circuit. Connect the red test lead to the
positive side and the black test lead to the negative side.
Turn ON power.
Read the current on the black DC scale. Use the 0-50 figures to read directly
in microamperes.
Turn power OFF and restore circuit to original condition.
Direct Current Measurement 0-1mA through 0-500mA
Set the function switch at + DC (Figure 4-7).
Plug the black test lead into the - COMMON jack and the red test lead into the
+ jack.
T
V
V
0
V
A
V
G
E
R
A
N
G
E
d
2 -
8 -
+
+
6
2
B
0
o t
0
o t
R
o t
o t
A
+
+
+
2
N
3
+
1
2
6
5
G
0
0
E
21
!
R
R
A
A
A
E
e
d
d
d
a
d
d
d
A
d
D
+
+
+
i d
1
2
4
N I
2
6
0
e r
G
d
d
d
c
B
B
B
y l t
o t
o t
o t
e r
e r
e r
a
a
a
d
d
d
n i
n i
n i
g
g
g