to relay Kl is broken. Simultaneously , an alter-
nate path is provided by contacts K3A (l&4) when
K3 de-energizes which keeps “S” panel trouble re-
lay Kl energized.
The current flow in a power failure condition is
from K3B terminal 8, through the milliameter (if
used), K4B terminal 6, contacts K4A (4&l), the
telephone line, the remote station, the telephone
line, contacts K4B (8&5), contacts K3A (4&l),
K4A terminal 3, relay K 1, resistor R2, K 1 terminal
8, diode D 1 to +24VDC at Kl terminal 1.
SYSTEM TROUBLE CIRCUIT
Trouble Condition
When a trouble occurs in the 4208 system (other
than AC power failure) a “trouble” signal is sent
from terminal 5 on the “A” panel to K2 terminal
7 on the “S” panel which energizes K2 and causes
its contacts to transfer.
When the K2A contacts transfer, the normal su-
pervision circuit is broken through contacts K2A
(4&l) but an alternate path is provided by contacts
K2A (l&3) to keep “S” panel supervision relay Kl
energized.
The current path to “S” panel supervision relay
Kl is from K3B terminal 8 (-24VDC) through K3B
terminal 6, resistor Rl, contacts K2A (3&l), K3A
terminal 1, K4A terminal 3, relay Kl, resistor R2,
Kl terminal 8, diode Dl to +24VDC at Kl termi-
nal 1.
ALARM CIRCUIT
Alarm Condition
When an alarm is initiated within the 4208 sys-
tem, -24VDC is applied to the “S” panel at K4 ter-
minal 7 which causes alarm relay K4 to energize.
When the K4 contacts transfer, the polarity of
the potential that is normally applied to the remote
station is reversed and this causes the remote sta-
tion to indicate an alarm condition.
Current flows from K3B terminal 8, through the
milliameter (if used), contacts K4B (6&8), the tele-
phone line, the remote station (activating the sta-
tion), the telephone line, contacts K4A (l&3), re-
lay Kl, resistor R2, terminal 8, diode D 1 to +24
VDC at K 1 terminal 1.
“S” panel supervision relay Kl remains energized
during a system trouble condition but the remote
station is bypassed by contacts K2A (l&3) which
causes a “trouble” indication on the remote station
panel.
41
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