BE1-50/51B
4
The instantaneous reset characteristic forces the timer to
zero when the input current falls below 95% of setting.
This fast reset characteristic prevents the ratcheting
effect on electro-mechanical relay disks that occurs for
repeated faults.
The decaying reset characteristic replicates the decay-
ing reset of electromechanical relay disks. Models with
style numbers in the 200 series continue the decaying
process even when the input current goes to zero.
Models with style numbers in the 100 series reset imme-
diately when the input current drops below the minimum
required to power-up the relay (.5A for 5A models and
0.1A for 1A models).
TIME DIAL RANGE AND ACCURACY
The TIME DIAL range is 0.0 to 9.9 in 0.1 steps. A setting of
0.0 results in instantaneous operation without intentional
time delay.
INSTANTANEOUS ELEMENT CHARACTERISTICS
The characteristic for phase faults is faster because the
relay will be powered-up. However, the tripping charac-
teristic for ground applications is slightly longer to allow
time to power-up the relay. This longer trip time for
ground applications is beneficial because it helps avoid
nuisance trips. These timing characteristics are shown in
Figure 3.
Additional definite time delays of 0.1, 0.2 or 0.3 seconds
may be added to the instantaneous element on 100
series units; 200 series units have only 0.1 seconds. The
definite delay is determined by switches on the circuit
card.
OUTPUTS
Separate output contacts are provided for the TIME (51)
and INST (50) trip functions. An additional auxiliary
output relay (51 AUX) is included. This output operates
simultaneously with the TIME output relay. All output
contacts are configured normally open (NO).
MANUAL TRIP TESTING
The relay is provided with front panel test points to allow
shorting the output terminals to verify external control
circuit wiring.
TARGETS
Two target indicators are provided as a standard feature
of the BE1-50/51B. These magnetically latched, current
operated targets provide visual indication of trip by the
TIME or INST output contact. These targets must be
manually reset after the abnormal condition has been
removed or corrected.
Actual curve constants are available in the Instruction
Manual. See page 1 of this bulletin for applicable
publication number.
The Active/Pickup LED on the front panel will turn red
when the applied current just exceeds the PICKUP
setting.
RESET
Reset occurs when the current level is less than pickup.
Internal switch provides selection of either an Instanta-
neous or a decaying reset characteristic.
OUTPUTS
The TIME contacts (51 and 51AUX) are closed in
accordance with conditions defined by the selected time
characteristic equation and the sensed current magni-
tude. If the sensed current exceeds the INST PICKUP
setting, the INST contacts (50) are closed.
Breakers controlled by the output contacts can be manu-
ally trip tested by inserting a jumper between the TIME
and INST MANUAL TRIP test points on the front panel.
TIME ELEMENT CHARACTERISTIC SHAPES
FOR CO and BS142 CURVES
All time characteristic curves follow the relation:
T
T
= AD + BD + K = Time to trip
M
N
-C
T
R
= RD = Time for decaying reset
M
2
-1
Table 2.
Curve Type
Basler
Type
Similar To
S1
Short Inverse
ABB CO-2
S2
Short Inverse
GE-IAC-55
200 series only
L1
Long Inverse
ABB CO-5
L2
Long Inverse
GE IAC-66
200 series only
D1, D2
Definite Inverse
ABB CO-6
M1, M2
Definite Inverse
ABB CO-7
I1
Inverse
ABB CO-8
I2
Inverse
GE IAC-51
200 series only
V1
Very Inverse
ABB CO-9
V2
Very Inverse
GE IAC53
200 series only
E1
Extremely Inverse
ABB CO-11
E2
Extremely Inverse
GE IAC 77
200 series only
B
British Standard
BS 142-B
Very Inverse
C
British Standard
BS 142-C
Extremely Inverse
F
Fixed Time
none
FUNCTIONAL DESCRIPTION, continued
