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Instructional Booklet
Effective: June 2007 Page 3
Instruction Manual for the Eaton RTC-50
Automatic Transfer Switch Controller
A standard RTC-50 controller will:
•Monitor Utility and Generator power source voltages
•Provide undervoltage protection of the Utility and Generator
power sources
•Permit easy customer set-up
•Provide source status indications
•Provide remote indication that generator maintenance needs to
be performed
1.4 Glossary
With respect to their use within this document and as they relate
to transfer switch and controller operation, the following terminol-
ogy is defined.
Available
A source is defined as “available” when it is within its undervolt-
age setpoint range.
Connected
Connected is defined as when the input is shorted by an external
contact or connection.
Failed or Fails
A source is defined as “failed” when it is outside of the applicable
voltage ranges for the nominal voltage and for a time exceeding
0.5 seconds after the time delay emergency fail (TDEF) time
delays expires.
Failsafe
Failsafe is a feature that prevents disconnection from the only
available power source and also forces a transfer or re-transfer
operation to the only available power source.
Re-Transfer
Re-transfer is defined as a change of the load connection from the
Generator to the Utility.
Utility
Utility is the primary source (normal source, normal power source,
or normal).
Generator
Generator is the secondary source (emergency source, emergency
power source, emergency, standby, or backup source).
Utility: Failed or Fails
Utility is defined as “failed” when it is outside of its undervoltage
setpoint range.
Generator: Failed or Fails
Generator is defined as “failed” when it is outside of its undervolt-
age setpoint range for a time exceeding 0.5 seconds after the
TDEF time delay expires.
Transfer
Transfer is defined as a change of the load connection from the
Utility to the Generator power source.
Unconnected
Unconnected is defined as when the input is not shorted by an
external contact or connection.
1.5 Functions/Features
The primary function of RTC-50 controller is to accurately monitor
the Utility and Generator power sources and provide the necessary
intelligence to operate the ATS in an appropriate and timely man-
ner. In addition, the RTC-50 controller provides status information
through on-board and remote indicators.
The following is a list of the features of the RTC-50 controller.
1. Time Delay Normal to Emergency (TDNE)
This feature provides a time delay when transferring from the
Utility to the Generator power source. Timing begins when
the Generator becomes available. It permits controlled trans-
fer of the load circuit to the Generator.
Jumper selectable at 20 or 50 seconds. Default is 20 sec-
onds.
3. Time Delay Emergency to Normal (TDEN)
This feature provides a time delay of the re-transfer operation
to permit stabilization of the Utility source. Timing begins
when the Utility becomes available. If the Generator fails
during timing, then re-transfer is delayed for up to 6 seconds
to allow the Generator to recover.
Fixed setting of 10 seconds
5. Generator Monitoring and Protection
This feature provides monitoring and protection based on the
Generator voltage setpoints. All feature 5 functions are fail-
safe operations.
5J. All Phase Undervoltage Protection
Dropout: 168 Vac (70% of 240 Vac nominal)
Pickup: 192 Vac (80% of 240 Vac nominal)
7. Time Delay Emergency Fail (TDEF)
This feature provides a time delay that prevents a connected
Generator source from being declared “failed” in order to
override momentary generator fluctuations. If the Generator
remains in the failed state then, after the TDEF timer expires,
the transfer switch will proceed with the programmed
sequence for re-transfer.
Fixed setting of 6 Seconds
12. Power Source Annunciation
This feature provides LEDs to indicate power source availabil-
ity.
12G. Utility - Available
This feature provides a green LED that, when lit, indicates
that the Utility is available.
12H. Generator - Available
This feature provides a red LED that, when lit, indicates that
the Generator is available.
15M. Load Shed
Two sets of contacts are available and can be used to control
large connected loads on the Generator (i.e. air conditioners,
hot tubs, etc.). The contacts are rated for 250 Vac, 5 amps.