TM 11-6130-413-40
CHAPTER 2
FUNCTIONING OF EQUIPMENT
2-1. General.
hour rate until the critical voltage is detected, then
dropped to the lower rate for the remaining time.
This chapter describes the functioning of Battery
b. Battery Dischurge. Battery discharge is accom-
Charger-Analyzer AN/USM-432.
plished at a constant current rate by power transistors
2-2. Functional Description
Q3 through Q6 in a control loop with the current-sens-
ing shunt. Fixed high-wattage power resistors are
switched in parallel with the pass transistors Q3-Q6
to accomplish the higher discharge ratings. Two power
er-analyzer, showing input and output power and bat-
transistors, Q1 and Q2, in series with the discharge
tery connections, general circuit board logic and re-
circuit, provide isolation during charge pulses; during
lated switching. Figure 2-2 is a simplified logic dia-
the charge cycle, these transistors are biased off to
gram showing the timing and control functions, Fig-
protect the discharge circuit.
ure FO-1 is a schematic diagram of the charger-analy-
c. Timing and Control. Three synchronous timers
zer. Basic functions, charge, discharge, timing and
are included: two are used for the two charge func-
control, are as follows:
tions; and one timer is used for discharge. Each timer
is basically an electric clock with cam-operated
tery charger circuits include power transformer T1
switches. Operation of the switches occurs at 60 min-
and power switching and output voltage control SCR's,
utes for the charge timer, and at 60 and 120 minutes
Q7 and Q8. This is a pulse-type charger with both
for the discharge timer (2 switches). Because the
SCR's connected in a full-wave circuit with zero-cross-
charger/ analyzer can operate on either 50 Hz or 60 Hz,
over gating. Current pulses from the shunt, R17, are
a reversible panel overlay is used for timer control
integrated and compared with the average rate set by
markings. One side of the panel is graduated for unit
the front panel CHARGE AMP HR control. When
operation on 50 Hz supply, the other side is graduated
pukes equal or exceed the average charging rate de-
for operation on 60 Hz supply. (Panel is factory-in-
sired, the SCR gates are held off until the next period
stalled with 60 Hz graduations exposed.) To operate
begins. There are 120 counts in each cycle and each
the timers, the operator sets the knob to the position
gate is of a 60 Hz period (120/120=1 second per pe-
marked START. The timer remains at this position un-
riod). During this initial step of charging, the battery
til the logic starts the timer, which then runs until it
is below the critical voltage and it can accept very high
reaches the 60 minute mark (CHARGE) and trips the
switch. The discharge timer, in AUTO, runs until End
characteristic is useful because the critical voltage is
of Discharge (EOD) takes place, or for 120 minutes. In
reached earlier in the cycle as a battery ages. Once the
manual, the discharge timer runs for 120 minutes.
critical voltage is reached, the charging rate is reduced
Control circuits and include the current amplifier, the
to about one fifth of the initial rate, and it might re-
integrator and charge comparator, the voltage com-
quire completion of only about 15% of the charge with
parator, and the sequence logic as well as the power
fresh cells; or 25% or more of the charge with older
op-amp that drives the discharge transistor.
cells to reach critical voltage. For this reason batteries
are charged at a rate well above the "straight line" one
2-1
