§ 10 Connection diagrams.
The meters are connected to the network in two ways: directly to the network (direct connection meters) and through current and voltage transformers.
Fig. 1 Wiring diagram for single-phase meter.
Fig. 2 Diagram of direct connection of CP4-I679 meters with rated currents of 20 A or more into a three-wire and four-wire network.
Fig. 3 Diagram of direct connection of CP4-I678 meters with rated currents of 20 A or more into a three-wire and four-wire network.
Fig. 4 Diagram of direct connection of meters type CA3-I677 with rated currents of 20 A over a three-wire network.
Fig. 5 Wiring diagram for types of meters СР4У-И673М and СР4У-И679 with rated currents 1, 5А through any current transformers to a four-wire and three-wire network.
Fig. 6 Wiring diagram for the types СР4У-И673М and СР4У-И679 with rated currents 1, 5А through any current and voltage transformers to the three-wire network.
It should be noted that induction meters spin their disk faster when properly connected. Counters (especially when using current and voltage transformers) have many more reasons to spin more slowly than they should:
- Current transformers can be confused (instead of 3 pieces 300/5 there are 2 pieces 300/5 and one 600/5). However, a transformer with a lower coefficient can be installed, and then the counter will spin faster (though in this case the probability that this current transformer will burn from overload increases), and it is very easy to confuse - especially on old plates such vague that even on the removed transformer under with a lamp and with a magnifying glass it is not always possible to see what is written on them. And in the electrical panel, somewhere below it is completely unrealistic to see. We have to drag a whole bunch of devices.
- The beginning and end of one of the current transformers may be confused, then the 2 phases will wind forward and one back (although in the end the meter will wind forward, although less than expected)
- Phases in the meter may be confused. That is, a current transformer from phase A is connected to the meter at input 1, and the voltage comes from phase B. This is usually easily detected - the meter shakes back.
- Possible non-contact or breakage of one of the current transformers. Then the load of one of the phases will not be taken into account.
And if you digress a little, it is not always easy for an experienced electrician to switch to a pile of wires, especially when there are 3-4 meters on the panel. In this sense, the electronic ones are good because if something is connected wrong, they immediately swear (that is, they give an error message), but they are still expensive even for industrial enterprises.