7SR21 & 7SR22 Performance Specification
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1.2.5 Binary (Digital) Inputs
Nominal Operating Range
V
BI
19 V DC 17 V DC (minimum) to 290 V DC
88 V DC 74 V DC (minimum) to 290 V DC
1.2.5.1 Performance
Attribute Value
Maximum DC current for
operation
V
BI
= 19 V 1.5 mA
V
BI
= 88 V 1.5 mA
Reset/Operate voltage ratio
³ 90 %
Response time < 7 ms
Response time when programmed to energise
an output relay contact (i.e. includes output
relay operation)
< 20 ms
Sample Rate Every 5 ms
The binary inputs are isolated from earth potential. They have a low minimum operate current and may be set for
high speed operation. Where a binary input is both used to influence a control function (e.g. provide a tripping
function) and it is considered to be susceptible to mal-operation due to capacitive currents, the external circuitry
can be modified to provide immunity to such disturbances.
To achieve immunity from AC interference, a BI pick-up delay of typically one-cycle can be applied.
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