BE1-51/27C General Information
1-3
Timing option Z3 with option 2-D or 2-E, (switch selectable - 16 position) integrating extended B &
C curves:
!
Seven integrating inverse time with extended timing range
!
Nine integrating I
2
T with extended timing range
Characteristic curves are shown by the graphs in Figures 1-2 through 1-70. Note that each graph (i.e.
function) consists of a set of representative curves. Each curve (as well as any between-curve interpolation)
is selectable by the front panel
TIME DIAL
using a two-digit designation from 00 to 99. Because of space
limitations, each graph shows only 14 of the 100 possible selections.
Non-Integrating Timing
Timing options Z1 and Z2 and the characteristic curves available with those options use non-integrating
timing. Non-integrating timing is accomplished by timing at a gate that is not solely dependent on the
magnitude of the applied multiple of pickup current. The time-out value is calculated based on the type of
time curve characteristic selected, time dial setting, and the magnitude of the applied multiple of pickup
current. The time-out value is continuously updated during the timing cycle. When pickup is exceeded, a
timer is initiated. When the timer elapsed time exceeds the calculated time-out value, a time trip output
signal is generated.
This type of non-integrating time delay characteristic exhibits a dynamic characteristic that is immediately
responsive to changes of the applied multiple of pickup current.
Integrating Timing
Timing option Z3 and the characteristic curves available for that option uses integrating timing. Integrating
timing is accomplished by summing time increments that are based on the magnitude of the applied multiple
of pickup current, the time curve characteristic selected, and the time dial value. These time increments are
summed until a predetermined value is exceeded, then a time trip output signal is generated.
This type of integrating time delay characteristic simulates the operating characteristics of an
electromechanical overcurrent relay.
Built-In Test
A built-in test (BIT) switch mounted on the Logic Board provides diagnostic troubleshooting and calibration
in conjunction with the procedures provided in Service Manual, publication 9 1372 00 620.
OPTIONS
Timing
An extended timing option multiplies by approximately 5.7, the standard time delays. The resulting curves
are shown following the standard curves—e.g., Figure 1-2 is timing type B1 and Figure 1-3 is the timing type
B1 with extended timing range.
When timing option Z1, Z2, or Z3 is specified, a printed circuit board mounted selector switch allows a choice
of up to sixteen different time overcurrent functions. Timing option Z1 or Z3 may be further specified as stan-
dard or extended time, depending upon option 2 selection.
Sensing Input Type
When single-phase, two-phase-and-neutral, three-phase, or three-phase-and-neutral sensing has been
Summary of Contents for BE-51/27C
Page 1: ...0 1 2 3 4 5 67869 ABC DEF G 6H II GGJ KL M DEF DEK...
Page 16: ...BE1 51 27C Controls and Indicators 2 2 Figure 2 1 Location of Controls and Indicators...
Page 20: ...BE1 51 27C Controls and Indicators 2 6...
Page 22: ...BE1 51 27C Functional Description 3 2 Figure 3 2 Functional Block Diagram...
Page 32: ...BE1 51 27C Installation 4 7 Figure 4 10 Typical Internal Diagram Sensing Input Type L...
