7.5.7.2 Unsymmetrical current detection
Unsymmetrical current indicated if:
• any phase current is lower than CurrUnsymPU of the highest current in the three
phases.
• the highest phase current is greater than CurrRelPU of IBase.
If these conditions are true, an unsymmetrical condition is detected. This detection is
enabled to generate a trip after a set time delay tTrip if the detection occurs in the next
200 ms after the circuit breaker has received a command to open trip or close and if the
unbalance persists. The 200 ms limitation is for avoiding unwanted operation during
unsymmetrical load conditions.
The pole discrepancy protection is informed that a trip or close command has been
given to the circuit breaker through the inputs CLOSECMD (for closing command
information) and OPENCMD (for opening command information). These inputs can be
connected to terminal binary inputs if the information are generated from the field (that
is from auxiliary contacts of the close and open push buttons) or may be software
connected to the outputs of other integrated functions (that is close command from a
control function or a general trip from integrated protections).
7.5.8 Technical data
Table 58: CCRPLD (52PD) technical data
Function
Range or value Accuracy
Operate value, current
asymmetry level
(0-100) % ± 1.0% of I
n
Reset ratio >95% -
Time delay (0.000-60.000) s ± 0.5% ± 25 ms
7.6 Negative sequence based overcurrent function
DNSPTOC (46)
7.6.1 Identification
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Negative sequence based overcurrent
function
DNSPTOC
IEC09000132 V2 EN
46
1MRK 505 277-UUS C Section 7
Current protection
117
Technical Manual
To Next Page
Loading...
