Function
Range or value
Accuracy
Reset ratio
> 95%
-
Timers
(0.000-60.000) s
±
0.5%
±
10 ms
Operate time for current
detection
20 ms typically
-
Reset time for current
detection
10 ms maximum
-
8.6
Pole discrepancy protection CCRPLD (52PD)
8.6.1
Identification
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Pole discrepancy protection
CCRPLD
PD
SYMBOL-S V1 EN
52PD
8.6.2
Functionality
Circuit breakers and disconnectors can end up with their phases in different positions
(close-open), due to electrical or mechanical failures. An open phase can cause negative
and zero sequence currents which cause thermal stress on rotating machines and can cause
unwanted operation of zero sequence or negative sequence current functions.
Normally the affected breaker is tripped to correct such a situation. If the situation
warrants the surrounding breakers should be tripped to clear the unsymmetrical load
situation.
The pole discrepancy function operates based on information from the circuit breaker
logic with additional criteria from phase selective current unsymmetry.
1MRK 502 048-UUS A
Section 8
Current protection
247
Technical manual