Use and Care Manual

ManualsBrandsCummins Power Generation ManualsKitchen200-Amp Automatic Transfer Switch for RS20A Whole House Generator

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CONTROL TIME DELAYS

For transfer switches with an operator panel, the

transfer switch control uses various time delays to

break from one power source and connect to the

other source.

In the following descriptions of time delays, it is im-

portant to remember that:

S When the transfer switch is connected to the

Normal side, it is connected to the Utility

power source.

S When the transfer switch is connected to the

Emergency side, it is connected to the Gen-

erator power source.

Time Delay Engine Start (TDES)

This time delay prevents the generator set from

starting during brief utility power interruptions. This

timer starts the instant the utility fails, as detected by

the Undervoltage Sensor.

When the control senses a utility failure, the control

starts the Time Delay Engine Start (TDES) timer.

This time delay is set to 3 seconds.

If utility power returns while the TDES timer is ac-

tive, the timer is reset. When the timer expires, the

control signals the generator set to start. The timer

is not reset until utility power returns. If the Override

pushbutton is pressed while the TDES timer is ac-

tive, the TDES timer is immediately terminated and

the control signals the generator set to start.

Time Delay Engine Cooldown (TDEC)

This time delay allows the generator set to cool down

(under no load conditions) after the switch returns to

utility power.

The Time Delay Engine Cooldown (TDEC) starts

timing when the load is retransferred to utility power.

This time delay is set to 10 minutes.

When the TDES expires, the stop signal is sent to

the generator’s control to shut down the generator

and the timer is reset. Pressing the Override push-

button has no effect on this time delay.

Time Delay Normal to Emergency (TDNE)

(Transfer)

This time delay allows the generator set to stabilize

before the load is applied.

While connected to the utility, this time delay starts

after utility power fails and the generator set be-

comes available (the amber Generator Power

Available LED is lit). This time delay also starts after

the generator set becomes available when a with

load Test or Exercise period is activated.

The time delay is set to 5 seconds. If the generator

set fails any time during a TDNE, the control resets

the timer and restarts it once the generator set is

again available.

If the Override pushbutton is pressed while the

TDNE timer is active, the TDNE is terminated imme-

diately and the control transfers the load to the gen-

erator set.

Time Delay Emergency to Normal (TDEN)

(Retransfer)

While connected to Generator power, this time

delay allows utility power to stabilize before the load

is transferred back (retransferred) to the utility. This

delay also allows the generator set to operate under

load for a minimum amount of time before transfer-

ring the load back to utility power.

This time delay starts with the transfer switch con-

nected to the generator set and after the utility be-

comes available following an outage (The green

Utility Power Available LED is lit). This time delay

also starts when an active Test or Exercise period is

ended. After the delay, the transfer switch can re-

transfer the load to the utility power source.

The time delay is set to 10 minutes. If the utility fails

any time during this time delay, the control resets

the timer and restarts it once utility power becomes

available. If the generator set fails at any time during

this time delay while power is available, the timer

expires and the normal retransfer sequence takes

place.

If the Override pushbutton is pressed while the

TDEN timer is active, the TDEN timer is terminated

immediately and the transfer switch retransfers the

load back to the utility.