First of all, there is no precision and variable ratio of the high sensitivity of the 0 sequence current micro-transformer, this type of 0 sequence current transformer is mainly used in Neutral point ungrounded or by the arc suppression coil grounding system.
In the words of its small current line selection device should pay attention to the use of 0 sequence current transformer, because the small current line selection device itself does not have a fixed value, 0 sequence current is only one of the criteria used to carry out the device. Requires zero sequence current micro-transformer when the primary grounding current is relatively small, will be with non-metallic grounding, 0 sequence current micro-transformer is bound to have a certain output, and then can meet the door threshold of the device start.
The load impedance of the device itself does not appear to be particularly large, but at this point it will be necessary to connect the 0 sequential current miniature transformers and devices through the cable. In this regard, the impedance of its cable is the main load impedance of the 0 sequence current micro-transformer, the load impedance of this zero-sequence current micro-transformer is generally about 2.5ω, after years of practice and testing to know and small current line selection device supporting the 0-sequence current transformer selection: On its ratio is 150/5; capacity is 5VA or its variable ratio is 40/1, capacity is 2.5VA.
These two 0-order current miniature transformers are in the load impedance 2.5ω, a 1 A, two output in the 20mA or so, two times a 40A ≥1a, this time there will be no strict variation relationship. With DD11/60 type relay supporting the use of 0-sequence current micro-transformer: DD11/60 type relay coil parallel impedance is also in the 10ω,cosφ=0.8; manufacturers produced the ENR-LJ (K) xxa type 0 sequence current micro transformer is its supporting products, And in this case two times the current is in 60mA, in terms of its 0 sequence current micro-transformer on the first current, then that is less than or equal to 4 a can be. However, when it is used, the actual operating specifications should also be noted.