Hold 15 sec. to
start the engine
generator and to
transfer the load
to emergency.
Press to cancel the
active exercise period
(stops engine now or
after cooldown) See
page 5–1.
Hold 5 sec. to set
20 min. engine exercise
period immediately (engine
starts) and weekly thereafter.
➤
blinks slowly when
button is released (set)
and during 20 min.
exercise period.
➤
blinks rapidly when
button is held 5 sec.
while being set
Lights show position of transfer switch.
Lights show the sources accepted.
Light for built–in
engine exercise timer:
See page 5–1
for complete
instructions
Figure 2–1. Membrane controls and indicator lights.
➤
stays on after engine
stops (exerciser is
enabled for weekly
operation)
SECTION 2 SEQUENCE OF OPERATION
2---1
Transfer To Emergency
The sequence for load transfer to
emergency source begins automati-
cally when normal source voltage
falls below the preset dropout point
or when
Transfer Test
button is
pressed. An under voltage condition
on any phase of the normal source is
detected by the sensor.
When the normal
source voltage fails or
the
Transfer Test
button
is pressed, the SE relay
de-energizes and relay
NR begins its timing
cycle (1 or 3 seconds,
momentary
normal
source outage delay
).
The NR relay is provided with a time delay on dropout to
override momentary outages and prevent nuisance starting
of the engine-driven generator. If the normal source voltage
returns above the sensor dropout setting before the time
delay expires, the NR relay timing cycle is reset to zero and
relay SE energizes.
If the normal source voltage does not return above the
sensor dropout setting before the time delay expires, the
NR relay de-energizes and signals the engine-driven
generator to start. At the same time, a voltage and
frequency sensor begins monitoring the emergency source.
The sensor will accept the emergency source only when
both voltage and frequency reach preset pickup points.
Usually about ten seconds elapse from dropout of the NR
relay to acceptance by the sensor. This time span occurs
because the engine-driven generator must crank, start, and
run up to nominal pickup points. For this reason, if the
Transfer Test
button is pressed it must be held for 15 seconds.
If the emergency source is available immediately, the sensor
may accept it as soon as NR relay drops out.
When the emergency source is accepted by the sensor,
relay ER begins its timing cycle (
transfer to emergency
delay
). ER relay is provided with an adjustable (0 to 5
minutes) time delay on pickup to delay transfer of the
load to the emergency source. For immediate transfer
press
Bypass Time Delay
button.
ER relay energizes, the TS coil is energized, the transfer
switch operates, and all switch contacts (mains, controls,
auxiliaries) reverse position. The transfer switch is now
supplying the load from the emergency source.
The transfer switch will remain in the Emergency
position until the normal source is restored. If the
Transfer Test
button is used, the transfer switch will
remain on emergency until the
retransfer to normal delay
times out.
Retransfer to Normal
The sequence for load retransfer to the normal source
automatically begins when the voltage sensor detects
restoration of the normal source. The voltage level must
rise above the preset pickup point on all phases before
the sensor will accept the normal source.
When the normal source is accepted by the sensor, relay
SE begins its timing cycle (adjustable 1 sec. to 30 min.,
retransfer to normal delay
). For immediate retransfer
press
Bypass Time Delay
button. SE relay is provided with
a time delay on pickup to prevent immediate load
retransfer to the normal source. The delay insures that
the normal source has stabilized before reconnection of
vital loads. If the normal source voltage falls below the
present dropout point before the time delay expires, the
timing cycle is reset to zero. If the emergency source fails
for more than 4 seconds during the timing cycle, ER relay
drops out and the load is immediately retransferred to
the normal source, if that source is acceptable.
SE relay energizes and ER relay is dropped out. The TS
coil is energized, the transfer switch operates, and all
switch contacts (mains, controls, auxiliaries) reverse
position. The transfer switch is now supplying the load
from the normal source again.
Upon retransfer to the normal source, NR relay begins its
timing cycle (
unloaded running delay [engine cooldown]
).
NR relay is provided with a 5 minute time delay on pickup
to keep the engine running for a cool-down period.
NR relay energizes after the time delay and signals the
engine-driven generator to shut down. All circuits are
reset for any future normal source failure.
Activation of standard control features shown in Section 5
will alter the sequence of operation and introduce
additional time delays during transfer operations.
