System Setup and Setpoints – 4
4–65
AUTO TRIP (AT)
Path:
System/Setup/Setpoints/Auto Trip
The Auto Trip selection from the Transfer Settings
group (Figure 4-33) opens the Auto Trip Dialog
screen (Figure 4-65).
If an external operation closes the second breaker
while leaving the first one closed, and if the Auto
Trip feature is enabled, the MBTS will trip the
breaker that was originally closed within an
adjustable time delay (0 to 50 Cycles in increments
of 0.5 Cycle) after the second breaker is closed.
The Auto Trip operates in either direction to allow
external parallel transfer but prohibit inadvertent
parallel operation. It must be noted that the external
operation that closes the second breaker must be
supervised by means that are external to the motor
bus transfer system. Auto Trip is
not
a transfer, the
only command sent is a trip command after the
time delay and no other parameters are used to
supervise this operation.
For example, in an application where there are two
MBTS units connected in a main-tie-main
configuration (see Figure 4-66) it is recommended
to disable the Auto Trip feature. In this configuration
both units can operate a common tie breaker. If one
unit transfers by tripping its main breaker and closing
the tie breaker, then the other unit would now see
both of its breakers closed. Depending on the breaker
selected in the Auto Trip feature this unit would trip
either its main breaker and both motor buses would
be disconnected or it would trip its tie breaker that
was just closed, disconnecting the motor bus of the
unit that originally transferred. Neither of these
situations is desirable!
Auto Trip/Enable/Disable
In the top right corner of the screen is a command
button that will Disable or Enable the Auto Trip
feature.
Auto Trip/Breaker Trip Option
The Breaker Trip Option allows the selection of
which breaker to trip when both breakers are closed.
The selections include the “Just Closed Breaker” or
“Originally Closed Breaker”. Typically the Originally
Closed Breaker is tripped to allow an external Hot
Parallel Transfer.
Auto Trip/Tripping Command Time Delay
The Tripping Command Time Delay allows the user
to delay (0 to 50 cycles) sending the selected
Breaker Trip Option.
Auto Trip/Blocking Inputs Selection
The Blocking Inputs Selection
button opens the
Blocking Inputs Selection dialog screen (Figure
4-60). Any Input or the Fuse Loss (FL) function can
be selected to block an Auto Trip. When an input is
selected, it is not grayed out in other types of
transfers.
Auto Trip Save/Cancel
The Save selection saves the Auto Trip settings
either to an open file or to the target MBTS. Cancel,
returns the user to the previous open screen.
Summary of Contents for M-4272
Page 1: ...Instruction Book Book 1 of 2 M 4272 Motor Bus Transfer System ...
Page 45: ...xviii M 4272 Instruction Book This Page Left Intentionally Blank ...
Page 200: ...System Setup and Setpoints 4 4 89 Figure 4 93 ISSLogic Function Dialog Screen ...
Page 207: ...M 4272 Instruction Book 4 96 This Page Left Intentionally Blank ...
Page 214: ...Declaration of Conformity Appendix I I 1 IAppendix I Declaration of Conformity ...
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