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Hold 15 sec.to
start the engine
generator and t o
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
.toset
20 min. engine exercise
period immediately (engine
starts) and weekly thereafter.
³ blinks slowly when
button is released (set)
and during 20 min.
exercise period.
³ 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:
Seepage5–1
for complete
instructions
Figure 2–1. Membrane controls and indicator lights.
³ stays on after engine
stops (exerciser is
enabled for weekly
operation)
SECTION 2 SEQUENCE OF OPERATION
2 --- 1
Transfer To Emergency
Thesequenceforloadtransferto
emerg en cy source beg ins automati-
cally when normal source voltage
falls below the preset dropout point
or when Transfer Test button is
pressed. A n under v oltage condition
on any p hase of the normal source is
detected by the senso r.
Whe n the norma l
sour c e voltag e fail s or
the Tra nsfer Te st b utton
is pressed, the SE relay
de-energ iz es and relay
NR begins its timing
cycle (1 or 3 seconds,
momen t ar y no rmal
source outage delay).
The NR relay is provid ed with a tim e delay on dropout to
overr ide m om en tary o utag es an d prevent nu isan c e starting
of the engine-driven generator. If the normal source voltag e
retur ns abo ve the sensor drop out setting befor e the time
delay exp ir es, the NR r elay timing cycle is reset to zero and
relay SE energizes.
If the n orm al source voltag e does not r eturn above the
sensor drop out setting before the time d el ay expires, the
NR relay de-energ izes and signals the engine-driven
gen erator to s tart. At the sam e tim e, a voltage an d
frequenc y sensor b egins monitoring t he emerg enc y sou rc e.
The s ensor w ill accept the emergency source o nly when
both
voltage and fre quency reach preset pickup points.
Usually about ten seconds elapse from dropout of the NR
relay to acceptance by the sensor. This time span occurs
bec ause th e eng ine-dr iven g ener ator m us t c rank, star t, and
run up to nomin al pic ku p poin ts. For this reas on , if the
Tran sf e r Test button is p ressed it m ust be held for 15 seconds.
If the em ergenc y sour c e is avail ab l e i m m ed iately, the s ens or
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 t ransfer switch will remain in the Emergency
positi on until the normal source is restored. If t he
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.
Whenthenormalsourceisacceptedbythesensor,relay
SE begins its timing cycle (adjustable 1 sec. to 30 min.,
retransfer to normal delay). For immediate retransfer
press Bypass Time Delay button. SErelay 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 s ource is acceptable.
SE relay energizes a nd 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, NRrelay beginsi ts
timing cycle (unloaded running delay [engine cooldown] ).
NRrelay is provided witha 5 minute time delay onpickup
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
addition al time delays during transfer operations .