Basler BE1-50/51B-217, Instruction Manual, Page: 6 / 49

1-1
SECTION 1
GENERAL INFORMATION
DESCRIPTION
BE1-50/51B Overcurrent Relays are microprocessor based, non-directional phase or ground relays that
monitor the magnitude of a single phase ac current to provide accurate instantaneous and time
overcurrent protection for 50 hertz or 60 hertz power systems. BE1-50/51B-217 Overcurrent Relay is a
special, modified relay with software for a
Load Demand Characteristic Curve in place of the short
inverse standard curve. To select the Load Demand Characteristic Curve, position the CURVE select
switch to position S.
APPLICATION
General
The wide range of pickup settings and front panel selectable time characteristics permit applications
involving coordination with fuses, reclosers, cold load pickup, motor starting, and fixed time
requirements. Integrating reset functions are available to simulate the disk reset of electromechanical
relays. BE1-50/51B Overcurrent Relays have the following standard features.
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Independent time and instantaneous elements.
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A secure method to manually trip the breaker at the relay front panel.
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Direct reading front panel controls.
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Minimum pickup setting for safety during installation.
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Time characteristics extend to a pickup multiple of 40.
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Rugged draw-out construction with steel case.
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Magnetic latching targets retain indication without power.
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Built-in accuracy eliminates internal adjustments.
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Minimum transient overreach.
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Field selectable instantaneous or integrating reset.
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Field selectable 50 or 60 hertz operation.
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Field selectable fixed instantaneous delay (0.0, 0.1, 0.2, or 0.3 second).
Individual models are available for 1 ampere and 5 amperes sensing input currents and installed in A1 or
S1 cases. BE1-50/51B-217 Overcurrent Relays may be tested without removing the relay from the case.
Shorting contacts are provided for all current inputs when the connection plug or relay chassis is
removed from the relay case. Figure 1-1 shows the front panel of the BE1-50/51B-217 Overcurrent
Relay.
BE1-50/51B-217 Overcurrent Relays have many advantages over other overcurrent relays. The four
primary advantages are:
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Field selectable time characteristics.
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Very low burden.
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Self powered from the sensed current.
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Continuous automatic calibration.