TM 11-6130-266-15
by a negative signal from current regulating amplifier
conjunction with a voltage divider network, develops the
A2A1: and it provides the turn-on drive for the transient
difference or error signal between the actual (sensed)
suppressor if the series pass element drop exceeds
output voltage and the desired output voltage. (The
approximately 6 volts.
desired output voltage is determined by the setting of
g. Voltage and Current Control. The output voltage
R3). The error signal is then amplified before being fed
is compared by voltage regulating amplifier A2Q3
to pass driver A2Q1 via current mode gate A2Q4. From
(differential amplifier) through a sensing divider to a 9.0-
A2Q1, the error signal is applied to the series pass
volt, stable, temperature-compensated zener reference,
element, allowing it to compensate for the change in
diode A2CR1. Any error voltage is amplified, inverted by
output voltage.
A2Q2, and applied to the pass element base, closing the
(2) Current sensing. The current sensing
loop. The output voltage is adjusted by varying the
circuit consists of output current sensor A6R1, current
sensing divider ratio between preset limits, using DC
regulating amplifier A2A1, current mode gate A2Q4, and
OUTPUT ADJ potentiometer R3. The output current is
pass driver A2Q1. (A2Q4 and A2Q1 are also part of the
sensed by low-voltage series shunt resistor A6R1. A
voltage sensing circuit.) The current sensing signal is
voltage analog of the output current is developed by
applied to A2A1 via relay A1K2 and resistor A6R1. The
current regulating amplifier A2A1. The reference across
difference or error signal developed across A6R1 is
CURRENT LIMIT ADJ potentiometer A2R15 is chosen
applied to A2A1. The amplified error signal is then fed to
so that 26.5-ampere output current opens gate diode
A2Q1 via A2Q4. The output of A2Q1 is applied to the
A2CR4, providing constant current operation for any
series pass element, enabling it to provide accurate load
lower value of system load impedance.
current regulation.
h. Sensing Circuits. Both the voltage and current
sensing circuits are controlled by sensing transfer relay
i. Differences Between Models. In addition to the
A1K2. If the load has been transferred to an external
circuit descriptions provided previously in paragraphs a.
battery because of ac input failure, relay A1K2 trips and
through h., Power Supply PP-6224 A/U also includes the
cuts off voltage sensing signals. This action deactivates
following circuit changes for EMl reduction: (Refer to
the entire sensing circuit. Sensing is automatically
schematic diagram, fig. 8-4.).
resumed when normal ac input power is restored.
During the period normal ac power is applied to the
(1) Input power. Input and output power
power supply, 32 volts de furnished by the transfer
switching is similar to that described in para. a except
control is used to energize A1K1. This, in turn, connects
that relay A6K1 utilizes dual-contacts for reduced
dc power to power transfer relay A6K1. Once A6K1 is
contact bounce, greater reliability and current-carrying
made, it applies the output of the power supply to DC
capability. The output of the power supply is connected
OUTPUT receptacle J6 and DC OUT receptacle J7 and
via paired contacts B1-B2 and C1-C2 to DC OUT
J59. The output of the power supply is filtered for
receptacles J6-D and J7-B. Further, additional output
radiofrequency by A2L1-A2L6, A2C8-A2C13, C10-C13,
filtering and transient suppression for J6 is provided by
and FL2.
FL2 (C1 through C6) and output line shielding.
(1) Voltage sensing. The voltage sensing
circuit consists of DC OUTPUT ADJ potentiometer R3,
(2) Transfer Control. Switching operations for
voltage regulating amplifier A2Q3, current mode gate
connecting the external battery to the load in the event of
A2Q4, and pass driver A2Q1. (A2Q4 and A2Q1 are also
a power reduction or failure are as described in para. b
part of the current sensing circuit.) The voltage sensing
except that switching is accomplished via normally-
signal is routed to A2Q3 via relay A1K2 and DC
closed A6K1 contacts A2-A3, B2-B3.
OUTPUT ADJ potentiometer R3. The potentiometer, in
Change 3 43
