TRENDnet Series 300 manual Sequence Of Operation, Transfer To Emergency, Retransfer to Normal

to emergency.

generator and to (stops engine now or period immediately (engine transfer the load after cooldown) See starts) and weekly thereafter.

start the engine

Hold 15 sec. to

active exercise period 20 min. engine

Press until light FLASHES

Hold 5 sec. to set

Florham Park NJ 07932 USA

TRANSFER SWITCH TEST BYPASS TIME DELAY SET ENGINE EXERCISER

page 5–1.

Press to cancel the

Press for 15 Seconds

SECTION 2 SEQUENCE OF OPERATION

lights show position of transfer switch lights show the sources available

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 Switch Test button is pressed. An under voltage condi- tion on any phase of the normal source is detected by the sensor.

When the normal source voltage fails or the Transfer Switch 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 Switch 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 Switch Terst button is used, the transfer switch will remain on emergency until the retransfer to normal delay times out.

light for built–in

engine exercise timer

· blinks rapidly when button is held 5 sec. while being set

· blinks slowly when button is released (set) and during 20 min. exercise period.

· stays on after engine stops (exerciser is enabled for weekly operation)

See page 5–1 for complete instructions

Figure 2–1. Membrane controls and indicator lights.

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.

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