Basler BE1-24, Инструкция по эксплуатации

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RST
THS ×
ET
FST
× 100
RST
7.5 ×
30
50
× 100
450
BE1-24 Functional Description 3-3
OUTPUT FUNCTIONS
BE1-24 Volts Per Hertz Overexcitation Relays have two standard and one optional independent output
functions. Standard independent output functions are the inverse square timed trip and the definite time
alarm. The optional independent output function is the instantaneous trip function.
Inverse Square Timing
Inverse square timing is used for the timed trip function. This closely approximates the heating characteristic
of the protected equipment as overexcitation increases. A linear reset characteristic provides for the
decreasing (cooling) condition. The timed trip desired for the overexcitation condition is defined by front panel
thumbwheel switches (adjustable from 0.1 to 10.0 in increments of 0.1). The minimum time delay (TIME
DIAL setting 0.1) is fixed at 0.25 seconds, and the maximum time delay is approximately 1000 seconds.
Refer to Figure 1-4 or Figure 1-5. Because there is no TIME DIAL tens digit, a setting of 0.0 is equivalent
to a TIME DIAL setting of 10.0 and is the maximum time delay.
The Integrating Trip Timer, within the microprocessor, provides the inverse square timing function and the
reset function. Whenever the timed trip pickup setting is exceeded, the integrating trip timer begins ramping
up in accordance with the selected inverse square curve until a trip output is produced. But if the volts per
hertz condition falls below the pickup setting, the integrating trip timer will ramp down towards reset at a linear
rate that is based on the front panel RESET time dial.
Reset time may be expressed by:
where:
RST = Reset time (in seconds)
THS = Thumbwheel setting
ET = Elapsed time (time accumulated towards trip)
FST = Full-scale trip time (from selected curve of Figure 1-4 or Figure 1-5)
Reset rate is individually adjustable, using the front panel thumbwheel. Settings are from 0.1 to 9.9 seconds
per percent of full-scale trip time in 0.1 second increments. A setting of 0.0 enables reset to be
instantaneous.
For example, assume a time dial setting of 25 (curve 2.5) and a multiple of pickup setting of 1.2. The total
time to trip will be 50 seconds. If this exists for 30 seconds before being corrected (60% elapsed time), what
would the total reset time be for a reset setting of 7.5. Based on the equation for reset time, the equation
would look like this:
If the overexcitation condition returns prior to total reset (i.e. less than 450 seconds), timing resumes from
that point at the inverse square rate. If this condition recurs after 225 seconds, the time to trip for the second
event would be 35 seconds. Figure 3-3 illustrates the inverse time delay and reset time.