TYPE 4208 “Q”
LOW BATTERY DETECTION PANEL
INTRODUCTION
The “Q” panel is used to monitor the voltage lev-
el of the standby battery. If the battery voltage
falls below 22SVDC, the LOW BATTERY lamp on
the “Q” panel will illuminate and a “trouble” con-
dition will occur in the “A” panel.
LOW BATTERY DETECTION CIRCUIT (FIG. 19)
Normal Operation Reset Operation
The battery which is connected between termi-
nals 25 (-) and 28 (+) keeps relay K2 energized dur-
ing normal operation. Current flows from terminal
25, (-BAT) through variable resistor RI (Rl is ad-
justed so that K2 will de-energize if battery voltage
falls below 22.5VDC), relay K2 (energizing K2) to
terminal 28 (+BAT).
When the battery voltage is restored to its proper
level, the “Q” panel must be returned to normal
operation by operating the RESET switch on the
panel. When the RESET switch is operated, relay
K2 energizes. Current flows from terminal 25
(-BAT), through the RESET switch, terminal 21,
relay K2 (energizing K2) to terminal 28 (+BAT).
Low Battery Condition Operational Requirements
When the battery voltage falls below 22.5VDC,
relay K2 de-energizes and its contacts transfer. The
transferred K2A contacts apply -24VDC from ter-
minal 27, through contacts K2A (l&9) to terminal
26 where the current flow splits into two paths.
The “Q” panel is not to be field-adjusted or re-
paired. If it is suspected that a problem exists in
the “Q” panel, the following test is to be per-
formed:
One path is from terminal 26, through the LOW
BATTERY lamp (illuminating the lamp) to ter-
minal 28 (+BAT).
Disconnect the 4208 System from normal AC
power. (The System will then go to standby pow-
er, placing a load on battery.)
The other path is from terminal 26 through
diode Dl , terminal 22 to terminal 5 on the “A”
panel.
This -24VDC on “A” panel terminal 5
causes a
“trouble” condition in the “A” panel.
(Refer to “A” panel - Trouble Condition for de-
tailed circuit description.)
If
the battery voltage, under load, is between
22V and 23V, and the relay in the panel remains
energized (LOW BATTERY lamp out) it is to be as-
sumed that the Panel is good.
If the relay de-energizes (LOW BATTERY lamp
illuminated) under these conditions, it is to be as-
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