Load Program Selector Switches
SELECTOR switch can be placed in a different
position for accurate indication of a single-phase load
If n e i t h e r t h e D C C O M M O N BU S L OA D
current and power (KW). Any malfunction that shuts
PROGRAM SELECTOR switch (2, fig. 7-63) nor the
down the load bank drops the latch relay. This makes it
AC LOAD PROGRAM SELECTOR switch (5, fig.
necessary to place the AMMETER-WATTMETER
7-64) is in the CONTINUOUS position, the control
RANGE SELECTOR switch in the 160 KW/1600 A
circuit does not permit loads to be applied to either the
position once again after the malfunction is corrected.
dc or ac load sections of the load bank. Timed loading
ELECTRICAL SAFETY PRECAUTIONS
tests (5 minutes or 5 seconds) cannot be run
simultaneously in both the ac and dc sections.
Under normal conditions, technicians do not work
on energized circuits. But, when repairs on operating
DC Meter Range Selector Switches
equipment must be made, the work should be done
only by experienced personnel under the supervision
When dc power applied to the aircraft servicing
of the senior petty officer of the work center, if
input is used as the power source for the control power
possible.
circuit of the load bank, the DC AMMETER RANGE
SELECTOR switch (4, fig. 7-63) must be placed
When work on live circuits is necessary, every
initially in the 2000 A position to enable the LOAD
known safety precaution should be carefully observed.
SELECTOR switches by latching the relay circuit.
Ample light for good illumination should be
Once the circuit is latched, the DC AMMETER
provided.
RANGE SELECTOR switch can be placed in a
different position for accurate indication of the load
The worker should be insulated from ground
current. The DC AMMETER RANGE SELECTOR
with some suitable nonconducting material,
switch (8, fig. 7-63) in the jet starting circuit operates
such as several layers of dry canvas, dry wood, or
in the same manner--latching the relay circuit, when it
a rubber mat of approved construction.
is placed in the 2000 A position. Any malfunction that
The worker should, if possible, use only one
shuts down the load bank drops the latch relays. This
hand in accomplishing the necessary repairs.
makes it necessary to place the range selector switches
in the 2000 A position once again after the malfunction
Helpers should be stationed near the main switch
is corrected.
or the circuit breaker so the equipment can be
de-energized immediately in case of emergency.
Load Selector Toggle Switch
A person qualified in first aid for electric shock
The 450 amp LOAD SELECTOR toggle switches
should stand by during the entire period of the
(14, fig. 7-63) cannot apply 450 amp loads to the
repair.
aircraft servicing input unless the DC AMMETER
RANGE SELECTOR switch (4) is in the 1000 A or
High-Voltage Precautions
2000 A position. Similarly, the 450 amp LOAD
SELECTOR toggle switches (10) are inactive unless
Personnel s h o u l d n e v e r w o r k a l o n e n e a r
the DC AMMETER RANGE SELECTOR switch (8)
h i g h - vo l t a g e e q u i p m e n t . To o l s a n d e q u i p m e n t
is in the 1000 A or 2000 A position.
containing metal parts should not be used in any area
within 4 feet of high-voltage circuits or any electric
Ammeter-Wattmeter Range Selector Switch
wiring having exposed surfaces. The handles of all
metal tools, such as pliers and cutters, should be
When the ac power applied to the ac input
covered with rubber insulating tape. (The use of plastic
connectors or terminals is used as the power source for
or cambric sleeving or of friction tape alone for this
the control power circuit of the load bank, the
purpose is prohibited.)
AMMETER-WATTMETER RANGE SELECTOR
switch (8, fig. 7-64) must be placed initially in the
Before you touch a capacitor, short-circuit the
160 KW/1600 A position to enable the RESISTANCE
terminals to make sure that the capacitor is completely
and REACTOR LOAD SELECTOR switches (21 and
discharged. Grounded shorting prods should be
17), by latching a relay circuit. Once the circuit is
permanently attached to workbenches where electrical
latched, the AMMETER-WATTMETER RANGE
devices are regularly serviced.
7-67
