3.4.230
fault repetition time
time interval between interruption and re-application of the primary short-circuit current during a circuit breaker auto-reclosing duty cycle in case of a non-successful fault clearance
3.4.231
secondary loop resistance
total resistance of the secondary circuit
3.4.232
rated symmetrical short-circuit current factor
ratio of the rated primary short circuit current to the rated primary current
3.4.233
transient factor
ratio of the secondary linked flux at a specified point of time in a duty cycle to the peak value of its a.c. component
3.4.234
transient dimensioning factor
dimensioning factor to consider the increase of the secondary linked flux due to a d.c. component of the primary short circuit current
3.4.235
Low-leakage reactance current transformer
current transformer for which measurements made at the secondary terminals (while primary open-circuited) are sufficient for an assessment of its protection performance up to the required accuracy limit
3.4.236
high-leakage reactance current transformer
current transformer which does not satisfy the requirements of 3.4.235, and for which an additional allowance is made by the manufacturer to take account of influencing effects which result in additional leakage flux
3.4.237
rated equivalent limiting secondary e.m.f.
that r.m.s. value of the equivalent secondary circuit e.m.f. at rated frequency necessary to meet the requirements of the specified duty cycle
3.4.238
peak value of the exciting secondary current at Eal
peak value of the exciting current when a voltage corresponding to Eal is applied to the secondary terminals while the primary winding is open
3.4.239
factor of construction
factor reflecting the possible differences in measuring results at limiting conditions between direct test and indirect test methods
Note 1 to entry: The measuring procedure is given in 2B.3.3.
5 Ratings
5.3 Rated insulation levels
5.3.2 Rated primary terminal insulation level
Clause 5.3.2 of IEC 61869-1:2007 is applicable with the addition of the following:
For a current transformer without primary winding and without primary insulation of its own, the value Um = 0,72 kV is assumed.
5.3.5 Insulation requirements for secondary terminals
Clause 5.3.5 of IEC 61869-1:2007 is applicable with the addition of the following:
The secondary winding insulation of class PX and class PXR current transformers having a rated knee point shall be capable of withstanding a rated power frequency withstand voltage of 5 kV r.m.s. for 60 s.
5.3.201 Inter-turn insulation requirements
The rated withstand voltage for inter-turn insulation shall be 4,5 kV peak.
For class PX and class PXR current transformers having a rated knee point e.m.f. of greater than 450 V, the rated withstand voltage for the inter-turn insulation shall be a peak voltage of 10 times the r.m.s. value of the specified knee point e.m.f., or 10 kV peak, whichever is the
lower.
NOTE 1 Due to the test procedure, the wave shape can be highly distorted.
NOTE 2 In accordance with the test procedure 7.3.204, lower voltage values may result.
