9252000991 Rev N BE1-50/51B General Information 1-7
5 Ampere Unit Pickup
Setting Range: 1 to 99 Aac
Setting Increment: 1 Aac
Accuracy: ±2%, ±25 milliamperes at or above 1.0 ampere setting
Dropout
Dropout occurs at 95% of pickup value.
Curve Characteristics
BE1-50/51B instantaneous characteristic curves are similar to standard electromechanical instantaneous
units. However, the time to trip for ground applications is slightly longer than that for phase applications to
allow time to power up the relay. Longer trip time for ground applications is beneficial because it helps to
avoid nuisance trips.
For phase applications, the maximum time to trip is 3.5 cycles at a pickup multiple of 1.0, and 1.5 cycles
at a pickup multiple of 3.0. The corresponding times for ground applications are 4.5 and 1.75 cycles.
Figure 1-3 shows the instantaneous characteristic curves for maximum time to trip.
On 100 series relays, additional delays of 0.1, 0.2, or 0.3 seconds may be added with internal switches
SW3-2 and SW3-3. These delays apply to both phase and ground applications. Closing switch SW3-2
provides an additional delay of 0.1 second. Closing switch SW3-3 provides an additional delay of 0.2
second. Closing both switches SW3-2 and SW3-3 provides an additional delay of 0.3 second. Section 2
illustrates the location of SW3.
On 200 series relays, an additional delay of 0.1 second may be added with internal switch SW3-2. This
delay applies to both phase and ground applications. Closing switch SW3-2 provides the additional delay
of 0.1 second.
Figure 1-3. Instantaneous Characteristic Curves
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