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M-4272 Digital Motor Bus Transfer System
*NOTE: The 'new source' is defined as the source to which the bus is being transferred.
Breaker Closing Time and Breaker Failure Monitoring
The Breaker Closing Time Monitoring feature measures the breaker closing time each time a transfer occurs. If
this time varies by more than a selectable breaker closing time deviation of the programmed time, an alarm is
activated. The breaker closing time is measured from the time the close command is sent until the breaker status
indicates that the breaker is closed.
The selectable Adaptive Breaker Closing Time is provided. If it is enabled, a new setpoint of the breaker closing
time will be automatically updated to an average value of 8 breaker closing time's measurements; however the
setpoints of the breaker closing time are not permitted to write and change unless this feature is disabled.
The breaker status inputs are also monitored for breaker failure. The breaker is considered failed when the
breaker status has not changed state within a programmable time after a trip command is issued. When
Simultaneous Transfer mode is selected and a breaker failure occurs on the breaker that should have tripped, the
breaker that was just closed will be tripped. This prevents the new source* from being continuously connected
with the failed breaker, which could have a fault.
In addition to using the breaker status in determining when a breaker has failed, the current through the breaker
can also be used to determine if the breaker has operated. The loss of current after a trip can be selected to
provide a more positive indication of breaker operation. An instantaneous overcurrent breaker failure element with
a time delay (50BF) is provided to minimize breaker failure coordination margins.
Power up Self-Test and Continuous On-Line Testing
The system performs self test verifications when power is first applied to the unit. These include verifying the
operation of the multiplexer, programmable gain amplifier, analog to digital converter, DSP chip, Host processor
and all RAM chips. After the initial self test is complete and the system is operating normally, continuous self
check verification continues to check for correct operation of the system. The continuous self check verification
tests are performed in the background and do not effect the response time of the unit to emergency conditions.
In addition to the background tests, there are tests that can be performed in the diagnostic mode during periodic
off line system testing. These additional tests can exercise the relay outputs, check front panel LED operation,
verify input status operation, check pushbutton operation and communication operation.
Target/Status Indicators and Controls
The SYS OK LED reveals proper cycling of the microcomputer; it can be programmed to flash or to be illuminated
continuously. The SOURCE 1 BRKR CLOSED and SOURCE 2 BRKR CLOSED red LEDs illuminate when the
breaker is closed (when the 52a contact is closed). The SOURCE 1 BRKR OPEN and SOURCE 2 BRKR OPEN
green LEDs illuminate when the breaker is open (when the 52a contact is open). The 52 contact input can be
configured for either “a”, “b” or "a/b" inputs. The corresponding BRKR status LED will illuminate when any of the
conditions, events or unit functions activate.
Pressing and releasing the STATUS RESET pushbutton resets the STATUS LEDs if the conditions causing the
operation have been removed. Pressing and holding the STATUS RESET pushbutton will allow conditions,
events or functions that are picked up to be displayed. The PS1 and PS2 LEDs will remain illuminated as long as
power is applied to the unit and the power supply is operating properly. TIME SYNC LED illuminates when a valid
IRIG-B signal is applied and time synchronization has been established. The TRIP SOURCE 1, CLOSE
SOURCE 1, TRIP SOURCE 2 and CLOSE SOURCE 2 status indicators are latched due to the pulsed nature of
these commands. To provide information about which outputs were operated during the last transfer the
appropriate TRIP SOURCE 1, CLOSE SOURCE 1, TRIP SOURCE 2 or CLOSE SOURCE 2 LEDs in the Status
module are latched until reset or the next transfer.
Summary of Contents for M-4272
Page 1: ...Instruction Book Book 1 of 2 M 4272 Motor Bus Transfer System ...
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Page 200: ...System Setup and Setpoints 4 4 89 Figure 4 93 ISSLogic Function Dialog Screen ...
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Page 214: ...Declaration of Conformity Appendix I I 1 IAppendix I Declaration of Conformity ...
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