Model Rrt Transfer Switch Operation; Source Availability; Ats Control Sequence Of Operation; Time Delays - Kohler 14/20RES Operation Manual

2.10 Model RRT Transfer Switch
Operation
The RDC/DC generator set/transfer switch controller
manages automatic transfer switch (ATS) functions
when connected to a Kohlerr model RRT transfer switch
through the ATS interface board.

2.10.1 Source Availability

The Model RRT transfer switch supplies voltage
sensing data to the RDC/DC controller through the ATS
interface board. If the source voltage falls below the
undervoltage dropout setting, the source is considered
to have failed. See Figure 2-8.
Item
Accuracy
Undervoltage Dropout
Undervoltage Pickup
Figure 2-8 Voltage Sensing Parameters
2.10.2 ATS Control Sequence of
Operation
See Figure 2-9 for time delay settings.
Preferred Source Fails:
1. The load control contact opens.
2. The engine start time delay times out.
Time Delay
Engine Start
Transfer, Normal to Emergency
Transfer, Emergency to Normal
Load Control
Engine Cooldown
Figure 2-9 Time Delays
TP-6734 5/10
Setting
±5%
90% of Pickup
90% of Nominal
Setting Description
3 seconds Time delay after utility source is lost until the engine start cycle begins.
Guards against starting the generator set because of a brief change in
the utility source.
3 seconds Time delay after emergency source becomes available until transfer to
emergency source.
2 minutes Time delay after the utility source returns until transfer back to normal.
Ensures that the the utility source is stable before transferring from the
emergency source.
5 minutes Allows delayed connection of selected loads to the generator set.
Prevents simultaneous starting of large motors after transfer to the
emergency source. Recommended for delayed starting of air
conditioners.
5 minutes Runs the engine with no load after transfer from the generator set.
Engine stops before the time delay expires if the temperature drops
below the cooled-down temperature level, or if the temperature rises
during the cooldown cycle.
3. The generator set is signaled to start.
4. The generator starts and the emergency source
becomes available.
5. The normal-to-emergency time delay times out.
6. The transfer switch transfers to the emergency
source.
7. The load control contact time delay times out.
8. The load control contact closes.
Normal Source Returns:
1. The emergency-to-normal time delay times out.
2. The contactor transfers to the normal source.
3. The engine cooldown time delay times out.
4. The generator is signaled to stop.

2.10.3 Time Delays

Time delays are factory-set to the values shown in
Figure 2-9. An authorized distributor/dealer can adjust
time delays using a personal computer and Kohlerr
SiteTecht software.
Time delays described in this section operate only when
the controller is connected to a Kohlerr model RRT
transfer switch.
Section 2 Operation 27