Figure 3-3. Ac utum ranges.

TM 11-6625 -537-14-1

is converted to an equivalent dc voltage which is

lower position, adjusting voltage readout dials C

displayed as a root-mean-square (rms) value on

through E as required to maintain zero VOLTS

the VOLTS meter. The VOLTS meter indication

meter needle deflection, until the desired accuracy

may be in error, as explained in paragraph 3-4, if

is obtained. Refer to table 1-2 for recommended

the input voltage is not of a single frequency.

settings to be used.

P e r f o r m initial operation in accordance with

(9) Determine accurate voltage reading from

paragraph 3-5 and proceed with the following

voltage readout dials; be sure to note location of

steps:

decimal indication.

(1) Set voltage readout dials A, B, C, D, and

Examples: Voltage readout dials A, B, C, D, and

E to O.

E indicate 3, 8, 6, 5, and 9, respectively. If the

(2) Set AC-de polarity switch to AC.

RANGE switch was on 500, the decimal indicator

(3) Determine input voltage range and set

between C and D would be illuminated and the

N U L L and RANGE switches as specified in

voltage measured would be 386.59 volts dc. If the

figure 3-3. Select 500-volt range if approximate

RANGE control was on 5 and the decimal in-

value of voltage to be measured is unknown.

dicator between A and B illuminated, the voltage

(4) Connect voltage to be measured to input

measured would be 3.8659 volts dc.

terminals. Always connect grounded side of input

(10) Set NULL control to VTVM and

to lower input terminal.

disconnect voltage from input terminals.

(5) Read voltage from 0-500 or 0-1 scale on

c. Operation a s a C o n v e n t i o n a l A c V t u m

the VOLTS meter as required by figure 3-3.

( Accuracy Within 3 Percent of Meter Readings ).

V O L T S meter will deflect to the right when

Ac voltages between O and 500 volts may be

measuring all ac voltages.

measured with the electronic voltmeter when used

as a conventional vtvm. The unknown ac voltage

Input

VOLTS Meter

RANGE

AC NULL

Voltage

setting

Setting

Full Seal. Deflection

MULT

Range

VTVM

o to 500v 0c

0-500

500

o-100

Xl00

*o to 100v ac

500

VTVM

0-50

o to 50v ac

l* to 1O v ac

0-10

500

Xl00

X10

0-5

o to 5v oc

VTVM

o-l

500

* o 1o o. 1v oc

X100

.01

Xlo

VTVM

o to 0.5v ac

O - 0.5(500mv)

.01

*o to o. lv ac

O-O.l(100mv)

Xlo

X.1

* O to o.0lv ac

O- O. 01(1Omv)

,01

X.1

*o to o.oolv ac

O-o.oolv ac

.01

X.1

*AII five voltage readout dials must be set to O to utilize this range. (Full scale

is determlned by multiplying the NULL switch setting by the AC NULL MULT

indicated by the RANGE switch. )

EL6625-537-14-TM-6

Figure 3-3. Ac utum ranges.

d . Operation as Differential A c Voltmeter

internal voltage is controlled by the voltage

Accuracy Within 0.2 Percent of Voltage Readout

readout dials and is indicated by the voltage

Dials. The electronic voltmeter is used as a dif-

readout dial indicators. The root-mean-square

ferential ac voltmeter by converting the unknown

(rms) value of the unknown ac voltage may be

ac voltage to a proportional dc voltage which is

read directly on the indicators when the VOLTS

then compared with a known internal voltage,

meter indicates zero. The voltage readout dial

When the two voltages are equal, the VOLTS

i n d i c a t i o n may be in error, as explained in

meter will indicate zero. The magnitude of the

paragraph 3-4, if the input voltage is not of a

3-7