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Instruction Booklet
IB 70-8698
Instruction Manual for the Eaton RTC-100
Automatic Transfer Switch Controller
eaton Corporation
www.eaton.com
Effective December 2009
4.1.4.3 Operation
While the ATS is connected to the Utility (Primary) source, the J8
contacts on the RTC-100 will close and monitor the loads that are
being controlled. The starting KW that is measured when those
loads are initiated is kept in memory on the controller. Each time
each of those loads is initiated, that starting KW is recorded and
the oldest starting KW that was in memory is now removed. When
the controller is first energized, these memory locations are empty.
The very first time a load is recorded, that value will populate the 4
memory locations for that load. This allows the RTC-100 to maintain
a running average of the power required to start the 2 controlled
loads that are connected to J8. This method allows for the controller
to track the load throughout its life time and to actively adjust as the
load power requirements change due to age, use, etc. This ensures
that the loads are never applied to the generator if the generator
does not have enough usable KW to start/run these loads.
During a power outage, the generator is initiated and the customer
load is connected to the generator power. The contacts on J8 are
held in the OPEN position for the first 10 minutes that the load is
connected to the generator. This allows the generator to stabilize.
After the 10 minutes is over, the contacts will then begin to monitor
if the controllable load is being called for. If it is, the controller will
verify how much KW is currently available from the generator and
compare that to the amount of KW that is programmed into the 4
potentiometers discussed above. If the amount of KW is less than
the amount of KW available from the generator, the RTC-100 will
now close the contact and allow the controlled load to be energized.
In the event that the controlled load is an inductive load (i.e. Air con-
ditioner, pool pump, etc) both the starting KW and running KW will
be monitored and compared prior to energizing that load. If there is
enough running KW but NOT enough starting KW available from the
generator, the load will not be allowed to energize. Both the starting
and running KW setting must be met before the load will be allowed
to be started.
If the load on contacts 3 and 4 of J8 are initialized and the load on
contacts 1 and 2 of J8 are being called to start, and the KW is not
sufficient to start the priority load, the secondary load will be turned
OFF in order to allow the primary load to start. After the primary
load is started, the secondary load will be restarted, if enough KW
is available, after 10 minutes. If there is not enough KW to start the
primary load, the secondary load will be restarted after 10 minutes
and the controller will monitor the KW and attempt to restart the pri-
mary load once it senses the KW has changed.
Anytime a transfer occurs to generator with both sources available
(i.e. load test, utility load shed input, etc.), the loads will be turned
off prior to the transfer to decrease the amount of inrush current
placed on the generator during initial loading. The controlled loads
will then be restarted after a 10 minute delay and verification of KW
availability. Anytime there is a transfer from generator to utility, the
controlled loads will remain ON during the transfer.
At anytime while connected to the generator source and the con-
trolled loads are energized, if the running KW of the generator is
reached or surpassed, the controlled loads will be immediately
turned OFF to ensure that the generator has enough KW to supply
the uncontrolled loads. After a 10 minute delay, the RTC-100 will
begin to monitor the J8 contacts to check if it can apply the con-
trolled loads once again. This same scenario will occur if the voltage
output of the generator drops below 80% of nominal will the con-
trolled loads are connected. This is done to protect the uncontrolled
loads from low voltage and also to prevent the generator from shut-
ting down due to under voltage or under frequency.
If, for any reason, a controlled load is changed or replaced, the
RTC-100 memory for the loads may need to be reset (as the power
requirements may differ). This can be done by pressing and hold-
ing the reset button for 5 seconds. If this is not accomplished, the
memory can also easily be changed by energizing the load at least 4
times while the controllable load is connected to the utility source.
