BECKWITH ELECTRIC M-4272, Instruction Book

Page: 61 / 217

M-4272 Instruction Book
2–6
Transfer Methods
The type of transfer that occurs when a Manual
Transfer is initiated is determined by the Manual
Transfer settings. Whenever the Hot Parallel Transfer
is enabled the Manual Fast, Delayed In-phase and
Residual Voltage Transfers are disabled. Only when
the Hot Parallel Transfer is disabled can the Manual
Fast, Delayed In-phase and Residual Voltage
Transfers be enabled.
Fast Transfer
The conditions that are necessary to execute a Fast
Transfer are:
• No lockout/blocking conditions exist.
• The phase angle between the motor bus
and the new source is within the limit
setting.
• The delta voltage between the motor bus
and the new source is within the limit
setting. (If this setting is enabled)
• The delta frequency between the motor
bus and the new source is within the limit
setting. (If this setting is enabled)
• The transfer must be completed within the
Fast Transfer time window of 1 to 10 cycles.
Delayed In-Phase Transfer
The conditions that are necessary to execute a
Delayed In-Phase Transfer are:
• No lockout/blocking conditions exist.
• The conditions for Fast Transfer have not
been met. (If this setting is enabled)
• The delta voltage between the motor bus
and the new source is within the limit
setting. (If this setting is enabled)
• The delta frequency between the motor
bus and the new source is within the limit
setting.
• The phase angle between the motor bus
and the new source is changing and must
enter the first phase coincidence (first zero
degree crossing) within the Delayed In-
Phase Transfer time window (adjustable
from 10 to 600 cycles).
The Delayed In-Phase Transfer feature
includes two programmable advanced
breaker closing times for Source 1 and
Source 2 breakers to coordinate the closing
at the first phase coincidence.
Programmable breaker closing time is from
0 to 12 cycles.
Residual Voltage Transfer
The conditions that are necessary to execute a
Residual Voltage Transfer are:
• No lockout/blocking conditions exist.
• The conditions for a Fast Transfer have
not been met. (If this setting is enabled)
• The conditions for Delayed In-Phase
transfer have not been met. (If this setting
is enabled)
• The motor bus voltage decreases to less
than the Residual Voltage Transfer limit
setting (adjustable from 5 to 60 V) within
the incomplete transfer lockout time limit
setting (50 to 3000 cycles).
Hot Parallel Transfer
When the transfer operation is from Source 1 to
Source 2, the close command to the Source 2
circuit breaker is issued first. Then after receipt of
the breaker status contact confirmation that the
Source 2 circuit breaker has closed and the tripping
command time delay (0 to 30 cycles), the trip
command to the Source 1 breaker is issued.
When the transfer operation is from
Source 2 to
Source 1, the close command to the Source 1
circuit breaker is issued first. Then after receipt of
the breaker status contact confirmation that the
Source 1 circuit breaker has closed and the tripping
command time delay (0 to 30 cycles), the trip
command to the Source 2 breaker is issued.
In hot parallel transfer, it is necessary to confirm
that the circuit breaker has been closed after a close
command is issued to that circuit breaker. This will
prevent the motor bus voltage from becoming dead
if the circuit breaker fails to close and the other
breaker is tripped. This failure of the breaker to
close could be caused by electrical or mechanical
problems.
In hot parallel transfer, an auto-decoupling feature is
included to trip the breaker that was closed by the
transfer if the breaker requested to open has not
opened within the predefined paralleling time.
The conditions that are necessary to execute a Hot
Parallel Transfer are:
• No lockout/blocking conditions exist.
• The phase angle between the motor bus
and the new source is within the limit
setting.
• The delta voltage between the motor bus
and the new source is within the limit
setting. (If this setting is enabled)