g. An AC ampere monitoring system is used to measure the AC ampere output
of AC/DC systems. The AC ammeter, in conjunction with its range selector switch,
allows measurement of AC currents on two ranges: 0-100AC ampere and 0-400AC ampere
(fig 5). The AC ammeter phase selector switch in this monitoring system is used to
detect the phase balance of the system being tested. This is done by moving the
switch from A to B to C while observing the ammeter reading. When the meter
readings remain approximately the same, a balanced phase condition exists in the
unit being tested.
h. The AC voltmeter, AC voltmeter range selector, and AC voltmeter phase
selector are used to determine voltage and phase conditions in AC/DC systems under
test. There are two voltage ranges: 0-25AC volts and 0-50AC volts. The circuit
selector has four positions: OFF, T1-T2, T1-T3, and T2-T3. A balanced phase
condition can be detected by observing the meter indication as the switch is
rotated. Voltage differential of more than 1 volt between any two settings
indicates unbalanced phase conditions. When not in use, the AC voltmeter circuit
selector should be set to the OFF position.
3.
FRONT CONTROL PANEL.
a. Figure 8 gives a good view of the rectifier cooling chamber and shows
the front panel controls. The field current control is in the OFF position when
rotated fully counterclockwise. When rotated clockwise this rheostat varies the
field current through units under test.
b. The load current control is a rotary type rheostat. Use with the 0-25
switch. Its OFF position is fully counterclockwise. The load to the unit under
test is varied by rotating the load current control clockwise.
c. The speed of a unit under test is controlled by the drive speed control.
The high and low speed drive heads are driven by the varidrive. The drive speed
control, when rotated counterclockwise, increases the speed of the varidrive and,
therefore, the unit under test. When stopping the varidrive always reduce the
speed to at least one-quarter. Never move the drive speed control in either
direction when the varidrive is not in operation.
4.
CENTER CONTROL PANEL (FIG 7).
a. Variable DC power is controlled by the power supply switch and the power
supply control. The power supply switch is an ON-OFF circuit breaker type toggle
switch. The "power on" indicator lamp illuminates with the switch in the ON
position. The power supply control is a rheostat. The OFF position is fully
counterclockwise. Clockwise rotation varies the supply output from 0-32VDC.
b. The relay lamp switch selects the proper circuit for the relay closure
indicator lamp. It is a three-position toggle switch (12V-OFF-24V).
c. Overload protection for the regulator load resistor is provided by a
fuse, which is held under the screw cap of the regulator resistor fuse holder.
d. Battery charging time is set by the charge timer. The timer is divided
in 1 minute increments and can be set for a maximum of 120 minutes. When lit, the
battery charge lamp indicates that the battery charger controls are in the circuit.
OS 010, 3-P9
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