C2, TM 9-4425-1754-14
h. Overload protection. A fail-safe, resettable
protection system protects all ranges, except the
APPROXIMATE overload
l-and 10-ampere ranges, against overload within
trip level 1
the limits of 1,000 volts ac or dc and 20-ampere
Ac volts
Search-range
Digital range
Dc Volts
single surge. The approximate ac and dc voltage
Dc voltage:
overload trip levels for dc current, dc voltage, ac
0.1-1 v
25
18
1v
voltage, and resistance measurements are shown
1-10 v
100
10v
70
in table 3. The meter, converter, and current
10-100 v
100v
260
185
generator are protected against overload by a
1000 v
0.1-1 kv
NA
NA
Ac voltage :
network of solid state diodes which are shown as
25
0.1-1 v
18
1v
a double-arrow s y m b o l on the simplified
1-10V
70
100
10v
schematics. The overall measurement system is
10.100 v
100v
185
260
protected against overload with a disconnect
0.1.1 kv
1000 v
NA
NA
relay activated by either an overcurrent or an
Resistance:
1.10
x1
4
3
overvoltage sensor composed of solid state diode
10.100
X10
4
3
networks applied to the relay. The safe voltage
4
0.1-1 K
3
X100
selection for the various voltage ranges is made
1-10 K
4
3
X1K
by a network of neon lamps applied to the
10-100K
18
X10K
+100,--25
overvoltage sensor. The relay is electrically reset
0.1-1 mego
18
X100 K
+100,--25
with the D-cell used in the resistance
1
Measured between the test Ieads.
measurement system. The l-ampere range is
i. Circuit Disturbance Measurements.
protected by a fuse and a thermal circuit breaker
(1 ) Voltage and current. Circuit loading and
and the 10-ampere range is protected by a fuse.
current drain for ac and d c voltage
measurements using the digital and search
Table 3. Overload Protection
also shows the resistance inserted into an
APPROXIMATE overload
electrical or electronic circuit to measure dif-
trip level 1
ferent current values and the resulting loss in dc
Ac Volts
Search-range
Digital range
Dc volts
mv.
(2) Resistance. The current, voltage, and
D C current:
0.1 ma
10-100 p.a
4
3
power for resistance measurements with digit
1 ma
4
3
0.1-1 ma
wheel setting of 1 0 0 and 9 9 10 are shown in
1-10 ma
3
4
10ma
4
100 ma
10-100 ma
3
short circuit current, and maxim urn mid-scale
1 amp
0.1-1 amp
3
4
power for resistance measurement using the
4
1-10 amp
3
10amps
search mode of operation.
