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Model 410C
3-1. INTRODUCTION.
3-2. The Model 410C is used to measure AC and DC
voltage, DC current, and resistance. All measure-
ment inputs are located on the front panel; a DC out-
put connector is located on the rear panel. Front
panel controls and indicators are color coded. DC
voltage, DC current and resistance knobs and indi-
cators are in black; AC voltage controls and indica-
tors are in red.
3-3. ADJUSTMENT OF MECHANICAL ZERO.
3-4. The procedure for adjustment of mechanical
zero is given in Section V.
3-5. FRONT AND REAR PANEL DESCRIPTION.
3-6. Figure 3-1 describes the function of all front
and rear panel controls, connectors and indicators .
The description of each control, connector and indi-
cator is keyed to a drawing which accompanies the
figure.
3-7. OPERATING PROCEDURES.
3-8. There are five operating procedures: DC Volt-
age Measurements, Figure 3-2; DC Current Measure-
ments, Figure 3-3; AC Voltage Measurements, Fig-
ure 3-4; Resistance Measurements, Figure 3-7; and
Measuring DC Current in Nano-amperes, Figure 3-8.
Note
Ageing of the neon tamps in the chopper
assembly can cause a change in chopper
frequency which produces a slight osci-
llatory movement of meter pointer. If
this oscillatory movement is observed,
rotate Oac Freq Adj A3R5 (see Paragra-
graph 5-28) in the ccw direction until
oscillation of pointer stops.
3-9.
DC VOLTAGE MEASUREMENTS (Figure 3-2).
3-10. The Model 410C is normally floating; however
a shorting bar can be connected at the DC AMPLIFIER
OUTPUT connector on the rear panel. When the instru-
ment is floating, the COM Lead should not be connected
to voltages greater than 400 volts.
3-11. DC CURRENT MEASUREMENTS (Figure 3-3).
3-12. General instructions for the measurement of
DC current are the same as those given for DC volt-
age measurements, Paragraph 3-9.
01556-2
SECTION III
OPERATION
AC VOLTAGE MEASUREMENT (Figure 3-4).
3-13.
1
ONE SIDE OF ALMOST ALL POWER
DISTRIBUTION SYSTEMS IS GROUNDED.
EXTREME CAUTION MUST BE USED IF
DIRECT MEASUREMENT OF POWER
LINE VOLTAGES IS ATTEMPTED. IF
THE GROUND CLIP LEAD IS ACCIDEN-
TALLY CONNECTED TO THE UN-
GROUNDEDSIDE OF THE LINE. SEVERE
DAMAGE TO THE 410C IS POSSIBLE
BECAUSE OF THE SHORT CIRCUIT
CREATED.
CAN BE SAFELY MEASURED BY USING
THE PROBE TIP ONLY. CONTACTING
THE GROUNDED POWER CONDUCTOR
WILL GIVE A READING OF 0 VOLTS
WHILE
GROUNDED LEAD WILL GIVE FULL
VOLTAGE READING.
3-14.
Although the Model 410C indicates a full scale
AC range of 500 volts, the optional Model 11036A AC
Probe should not be connected to AC voltages in ex-
cess of 300 volts RMS. AC voltage referenced to a
DC voltage may be measured, but the AC Probe clip
(alligator type) must be connected to the ground
of the circuit under test.
WHEN MEASURING AC REFERENCED
TO DC, THE PEAK AC VOLTAGE PLUS
DC VOLTAGE CONNECTED TO TRE
PROBE MUST NOT EXCEED 420 VOLTS.
3-15. PRECAUTION WHEN MEASURING AC VOLT-
A G E .
3-16. Special considerations must be kept in mind
when making AC voltage measurements. These con-
siderations are discussed in the following paragraphs.
3-17. GENERAL CONSIDERATION OF COMPLEX
WAVEFORMS.
harmonics or spurious voltages will introduce error
in the meter indication since the meter has been cali-
brated to read RMS values of true sine waves while
the Model 11036A Probe is a peak-above-average
responding device.. The magnitude of error that may
be expected when harmonics are present on the mea-
sured waveform is indicated in Table 3-1.
3-18. VOLTAGE MEASUREMENTS AT FREQUEN-
CIES BELOW 50 CYCLES/SECOND. Voltage mea-
surements at frequencies as low as 10 cycles per
TM 11-6625-1614-15
Section III
Paragraph 3-1 to 3-18
POWER LINE' VOLTAGES
CONTACTING
THE
UN-
Waveforms containing appreciable
3-1
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