9137200997 Rev D BE1-51 General Information 1-5
SPECIFICATIONS
BE1-51 Time Overcurrent Relays electrical and physical specifications are as follows:
Sensing Input Burden
Less than 0.1 ohms per phase or neutral.
Sensing Input Rating
The maximum continuous rating is 20 A, 1 second current rating is 50X (times) the maximum tap current
selected, or 500 A, whichever is less. For ratings other than those specified by the time curves, the rating
is calculated as follows:
T
less) is (whichever A 500 or tap x 50
I =
where I = Maximum current
T = Time that current flows (in seconds)
Time Overcurrent Pickup Selection Range
Continuously adjustable over the current sensing input ranges specified in the Style Chart (Figure 1-1).
Time Overcurrent Measuring Accuracy
±2% of pickup setting.
When the TAP CAL control is fully CW, the actual pickup will be within ±5% of the front panel TAP
selector setting.
Time Overcurrent Dropout Ratio
Better than 92 of pickup level.
Instantaneous Overcurrent Pickup Range
Continuously adjustable over the range of 1 to 40 times the time overcurrent pickup setting.
Instantaneous Overcurrent Measuring Accuracy
±2% of pickup setting.
Instantaneous Overcurrent Dropout Ratio
Better than 98% of pickup level.
Instantaneous Response
Figure 1-2 shows the typical response for the instantaneous pickup element.
Figure 1-2. Typical Instantaneous Response Time
Courtesy of NationalSwitchgear.com
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