RXT Transfer Switch Manual

TP-6807 1/1612 Section 1 Description
Loads. The transfer switch can be connected to supply
all of the electrical loads in the home, or only the
essential loads such as the furnace, refrigerator, well
pump, and selected light circuits. Identify the essential
circuits that must be supplied during a power outage.
Verify that the generator set and transfer switch are
adequately rated to supply all of the selected loads.
Circuit breakers. Because the size and number of
circuit breakers required will vary with each application,
circuit breakers are not provided with the transfer switch
load center.
Determine the circuits that will be connected to the
transfer switch (essential loads). Identify the breakers
for those circuits in the main distribution panel.
The ATS load center requires Square D type QO
breakers. If the main distribution panel uses the same
type of breakers, the breakers can be moved from the
main panel to the load center. Otherwise, obtain new
Square D type QO circuit breakers. For each circuit, the
rating of the load center circuit breaker must match the
rating of the existing breaker in the main panel.
Up to 8 tandem breakers can be used in the 16-space
load center. Use Square D type QOT tandem breakers.
The 12-space load center uses only single breakers.
Verify that the total rating for all of the breakers used in
the load center does not exceed the rating of the transfer
switch.
1.4 Controller Interface Board
The Model RXT transfer switch is available with either
the standard interface board or the combined
interface/load management board. Both interface
boards connect to the RDC2 or DC2 controller on the
generator set.
1.4.1 Standard Interface Board
All ATS control functions are performed by the
RDC2/DC2 controller mounted on the generator set and
communicated through the interface board. The
controller interface board sends voltage sensing data to
the RDC2/DC2 controller and receives transfer and load
control signals from the RDC2/DC2 controller.
1.4.2 Combined Interface/Load
Management Board
The combined interface/load management board
perfoms all of the functions of the standard interface
board and also provides load add and shed based on
generator capacity. The combined interface/load
management board can be used with single-phase
generator sets equipped with the RDC2 or DC2
controller only.
Note: Do not install a load shed kit or a load control
module (LCM) on a system that includes the
combined interface/load management board.
Many appliances do not run continuously. Air
conditioners and furnaces, refrigerators, sump pumps,
and other appliances cycle on and off as needed. With
load management, less critical appliances can be
powered by the generator set when the more important
appliances are not running, allowing the use of a smaller
generator set than would be needed to run all of the
building’s electrical equipment at the same time.
The combined interface/load management board
provides an automatic load management system to
comply with Section 702.5 of NEC 2008. The installer is
responsible for ensuring that the power system
installation complies with all applicable state and local
codes.
The combined interface/load management board
automatically manages up to six residential loads.
D Two relays are included to control two independent
heating, ventilation, and air conditioning (HVAC)
loads.
D Four (4) pilot relays are provided on the combined
interface board for connection of customer-supplied
load-switching contactors/relays. See Figure 1-3 for
the specifications of the circuit board relays.
Up to four (4) Kohlerr 50 amp power relay modules
(GM92001-KP1-QS) or customer-supplied normally
closed power relays can be connected through normally
open relay contacts on the circuit board. See Figure 1-4
for specifications for customer-supplied relays.
Customer-supplied r elays must be either normally
closed or double-pole double-throw (DPDT) and
maximum 50 amps. Note that the load must be
connected to the normally closed contacts of the relay.
Kohlerr Power Relay Modules are recommended.
Note: Connect only non-essential loads to the load
shed kit.