The current transformer can be divided into two categories according to the use function, namely the measurement of current transformers and protective current transformers. It is often accompanied by sound or other phenomena, and it is more likely to get fire, so it will endanger the lives and equipment safety of nearby staff, so we should understand its principles and exception solutions. Let’s take a detailed understanding of "What are the wiring diagrams in the current transformer and an abnormal processing method.
[What are the wiring diagrams of the current transformer?
We divide the current transformers into measurement current transformers and protective current transformers and protective current transformers. This paper summarizes various current transformer wiring diagrams for reference.
First, the measuring current transformer wiring method
The measurement of the current transformer means that the measuring and metering device supplies grid current information within the normal voltage range.
1, ordinary current transformer wiring diagram
The primary side current of the current transformer is entry from the P1 terminal, from the P2 terminal; that is, the P1 terminal connection power supply side, the P2 terminal is connected to the load side.
The secondary side current of the current transformer flows out of S1, into the positive terminal of the current table, and flow into the current transformer secondary terminal S2 after the current meter negative wire column, in principle, in principle, the S2 terminal is grounded.
Note: Some current transformers primary nominal, L1, L2, secondary side nominal K1, K2.
2, wearing a heart current transformer wiring diagram
The inductor wiring is similar to the normal current transformer, and the P2 side of the transformer is passed from the P1 side of the transformer, and the secondary side wiring is the same as the ordinary transformer.
Second, the current transformer wiring diagram
The current transformer wiring is generally divided into four wiring methods:
Single current transformer wiring diagram
It can only reflect the case of single-phase current, suitable for the case where a phase current is required.
2. Three-phase fully star-shaped wiring and triangular wiring form Current transformer wiring diagram
Three-phase current doors can promptly understand the changes in three-phase load in time.
3. Two-phase incomplete star wiring form Current transformer wiring diagram
Many actual work is used, but is limited to three-phase three-wire system. It saves a current transformer, according to the three-phase vector and the principle of zero, the B phase current is calculated by the current of A and C.
4. Two-phase difference current wiring form Current transformer wiring diagram
It is also only used in three-phase three-wire circuit. The advantage of this wiring is that it not only saves a current transformer, but also uses a relay to reflect various phase short circuit faults in the three-phase circuit, i.e., the use of less relays to complete three Circulation, saving investment.
5. Other wiring methods
5.1 Original side series, subside series
The primary side of the current transformer is connected in series. The sub-series wiring diagram is shown below, and the effect of in series: the transformer ratio is unchanged, and the secondary rated load is doubled.
5.2 The original side is connected in series, the side side is connected
The primary side of the current transformer is connected in series, and the secondary side and coupling line diagram is shown below, the string is parallel: the transformer ratio is doubled, and the secondary rated load is doubled.
5.3 Original side, subside series
The primary side of the current transformer is parallel, the sub-series wiring diagram is shown below, the string is parallel: the transformer ratio is doubled, and the secondary rated load is doubled.
5.4 Parallel, side side
The primary side of the current transformer is connected in parallel, the secondary side and coupling line diagram is shown below, and the effect of the transformer is not changed, and the secondary rated load is doubled.
[Current transformer abnormal solution]
Current transformers are often accompanied by sound and other phenomena. When the secondary loop suddenly opened, a high induction potential was generated in the secondary coil, and its peaks reached a few thousand volts, and the staff of staff and equipment safety on the secondary loop, and high pressure may arc. At the same time, since the magnetic flux in the core has increased dramatically, it reaches a high saturation state. The core loss is serious, which may damage the rheological secondary winding. At this time, a non-sinusoidal wave is caused to cause the magnetic flux density, so that the silicon steel sheet is extremely uneven, thereby having a large noise.
First, the process of current transformer is on the opening
If this failure occurs, keep the load constant and deactivate the protection device that may be mishapped, and notify the relevant personnel to quickly eliminate.
Second, the processing of the current transformer secondary circuit disconnection (open circuit)
1, abnormal phenomenon:
a. Current table indication is reduced to zero, active, and reactive menu indicates that there is a swing, and the electric meter is slow or stopped.
b. Differential disconnect light word sign.
c. Current transformers make an abnormal sound or fever, smoke or secondary terminal wire discharge, fire, etc.
d. Referring to the relay protection device, or mishapped (this phenomenon only found the fault only after the circuit breaker accidentally joked the gate or refusal to trip the cross-level trip).
2, abnormal processing:
a. Immediately report the schedule of the fault.
b. Declaption according to the phenomenon is a current transformer that belongs to the measurement loop or the protection circuit. Before processing, it should be considered to be deactivated to cause miscibility.
C. Anyone to check the secondary circuit of the current transformer, you must stand on the insulated pad, pay attention to personal safety, and use the qualified insulation tool.
d. The secondary circuit of the current transformer causes a fire, and after cutting off the power, it can be fired with a dry cloth or dry fire extinguisher.
Third, current transformer body failure
When the current transformer failure has one of the following cases, the processing should be disabled immediately:
a. Internal abnormal sound, overheating, and is accompanied by smoke and focus.
b. Severe oil leakage, porcelain damage or discharge phenomenon.
c. Sprinkled fire or flow glue phenomenon.
d. The elongation of the metal expander significantly exceeds the predetermined value at the time of the ambient temperature.
The introduction of "What are the wiring diagrams of the brief analysis of the current transformer" and "Workaround of the Current Transformer", I hope you can understand "What are the wiring diagrams in the current transformer and the abnormal processing method" .