Precautions For 3 Phase Electricity Meter Connection

• Posted by morgan yhddb June 23, 2020 - Filed in Other - #3 Phase Electricity Meter  - 2,180 views

   

  The    3 phase electricity meter   has direct connection type bai, mutual inductor connection type, current du, voltage mutual inductor connection mode and other wiring methods.

  1. Three-phase dao electric meter direct access type:

  The direct access type is also called straight-through wiring, which can be directly accessed within the range allowed by the load function meter, that is, the current specification of the meter can meet the user's needs, and this method can be used.

  
  (1) 1, 2 is called U, which is the live wire of a three-phase four-wire electric meter, connected to the A-phase input terminal, and 3 to the A-phase output terminal;

  (2) 4 and 5 are called V, which is the live wire of a three-phase four-wire meter, connected to the B-phase input terminal, and 6 to the B-phase output terminal;

  (3) 7 and 8 are called W, which is the live wire of a three-phase four-wire electric meter, connected to the C-phase input terminal, and 9 to the C-phase output terminal;

  (4) A, B, C three-phase outlet termination load;

  (5) 10 is connected to the neutral line, and then the wiring behind.

  2. The three-phase electric meter is connected through the transformer:

  When measuring the power consumption of a single-phase circuit with a large current, a three-phase power meter, because the current flowing through the line is very large, such as 300-500A, it is impossible to use the direct access method. The current transformer should be used for current conversion. The current is replaced with a small current, that is, the current that the energy meter can withstand, and then measured.

  (1) 1, 4, 7 should be connected to the S1 terminal on the secondary side of the current transformer, which is the incoming end of the current;

  (2) 3, 6, 9 must be connected to the S2 terminal of the secondary side of the current transformer, which is the outlet end of the current;

  (3) 2, 5, 8 are connected to A, B, C three-phase power supply;

  (4) 10 is connected to the neutral line. Generally, for safety reasons, the S2 terminal of the current transformer must be connected to ground.

  Note: The current measurement sampling of each current transformer must be kept in phase with its voltage sampling, that is, 1, 2, 3 are a group; 4, 5, 6 are a group; 7, 8, 9 are a group.

  3. The three-phase electric meter is connected through the current and voltage transformers:

  When measuring large currents and voltages with three-phase electricity meters, because the voltages and currents are so large that they cannot be directly connected, voltage and current transformers should be used for voltage and current conversion, and large voltages and currents should be replaced with small voltages and currents. That is, the voltage and current that the energy meter can withstand, and then measure it.

  (1) 1, 4, 7 should be connected to the S1 terminal on the secondary side of the current transformer, which is the incoming end of the current;

  (2) 3, 6, 9 must be connected to the S2 terminal of the secondary side of the current transformer, which is the outlet end of the current;

  (3) 2, 5, 8 are connected to voltage transformers respectively;

  (4) 10 should be connected to the neutral line and grounded together with the voltage transformer;

  Matters needing attention in the connection of three-phase electric energy meter:

  In actual work, the three-phase electricity customers contacted by power supply employees are often low-voltage power supplies, and most of them use mechanical three-phase four-wire energy meters.

  When the energy meter is installed, it can also be powered on to check whether the energy meter is rotating and the speed is normal, but it is often ignored to test whether the three-phase voltage phase sequence is correct.

  If a reactive energy meter is installed, the correctness of the phase sequence can be judged by observing whether the reactive energy meter is rotating forward. However, if only the energy meter is installed, the correct phase sequence cannot be judged by the forward rotation of the energy meter.

  Because when the reverse phase sequence is connected, the three-phase active energy meter can still rotate forward. Therefore, in order to avoid the latent and additional errors caused by the reverse phase sequence on the three-phase energy meter, after the three-phase energy meter is installed, it is necessary to conduct a power-on inspection test, and use the phase sequence table to re-test whether the three-phase voltage phase sequence is correct.

  If it is a reverse phase sequence, you can change the two-phase input and output lines to a positive phase sequence. When the phase sequence of the energy meter with transformers, it should be noted that the voltage and current of the same phase must be replaced at the same time to be correct.

  
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