BECKWITH ELECTRIC M-4272, Instruction Book

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M-4272 Digital Motor Bus Transfer System
†
Select the greater of these accuracy values. Accuracy applies to sinusoidal voltage with constant amplitude and
frequency. Values in parentheses apply to 1 A CT secondary rating.
50
BF1
50
BF2
27B
FUNCTIONS
Setpoint
Ranges
Increment Accuracy †
27B Bus Phase Undervoltage
Pickup #1, #2, #3, #4 5 to 120 V 1 V 0.5 V or 2%
Inhibit Setting** 5 to 120 V 1 V 0.5 V or 2%
Time Delay 1 to 8160 Cycles 1 Cycle -1 to +3 Cycles or 0.5%*
* The pickup and time delay accuracies apply to 60 HZ models at a range of 57 to 63 Hz, and to 50 Hz models at
a range of 47 to 53 Hz. Beyond these ranges, the time delay accuracy is 6 Cycles or 0.75% for the bus frequency
down to 25 Hz. The time delay accuracy is
O O O O O
20 Cycles or 1% for the bus frequency at a range of 5 to 25 Hz.
** The Voltage Inhibit setting can be enabled or disabled.
27B #1 is the Bus Phase Undervoltage initiate function that is used for Automatic Transfer from S1 to S2 direction.
27B #2 is the Bus Phase Undervoltage initiate function that is used for Automatic Transfer from S2 to S1 direction.
27B #3 can be used for load shedding.
27B #4 can be used for alarm or trip function.
The 27B functions are applicable only when the bus phase voltage input is applied.
50S1 Instantaneous Phase Overload Detection (Source 1)
Pickup #1, #2 1.0 to 100.0 A 0.1 A 0.1 A or 3%
(0.2 to 20.0 A)* ( 0.02 A or 3%)
Time Delay 1 to 8160 Cycles 1 Cycle 2 Cycles or 1%
* Values in parentheses apply to 1A secondary rating. Since this is only a single phase element, the 50S1
Function can only be used for overload detection and not used for overcurrent protection.
50S2 Instantaneous Phase Overload Detection (Source 2)
Pickup #1, #2 1.0 to 100.0 A 0.1 A 0.1 A or 3%
(0.2 to 20.0 A)* ( 0.02 A or 3%)
Time Delay 1 to 8160 Cycles 1 Cycle 2 Cycles or 1%
* Values in parentheses apply to 1A secondary rating. Since this is only a single phase element, the 50S2
Function can only be used for overload detection and not used for overcurrent protection.
50BF-1 Breaker Failure (Source 1)
Pickup Current 0.10 to 10.00 A 0.01 A 0.1 A or 2%
(0.02 to 2.00 A)* ( 0.02 A or 2%)
Time Delay 1 to 30 Cycles 1 Cycle 1 Cycle
50BF-1 can be initiated from designated M-4272 output contacts or programmable inputs.
* Value in parentheses apply to 1A Secondary Rating
50BF-2 Breaker Failure (Source 2)
Pickup Current 0.10 to 10.00 A 0.01 A 0.1 A or 2%
(0.02 to 2.00 A)* ( 0.02 A or 2%)
Time Delay 1 to 30 Cycles 1 Cycle 1 Cycle
50BF-2 can be initiated from designated M-4272 output contacts or programmable inputs.
* Value in parentheses apply to 1A Secondary Rating
50
S1
50
S2