What are the common faults of switch cabinets and ring network cabinets?

What are the common faults of switch cabinets and ring network cabinets?

Common switchgear faults include the following categories:

(1) Misoperation and refusal to operate faults. Such faults may be caused by mechanical faults in the transmission system and operating mechanism, or by electrical control and auxiliary circuit problems; The mechanical faults of the operating mechanism and transmission system are mainly manifested as mechanism jamming, component deformation, displacement or damage, loose and stuck opening and closing iron core, loose shaft pin, tripping failure, etc. Electrical control and auxiliary circuit faults are manifested as poor contact in the secondary wiring, loose terminals, incorrect wiring, burning of the opening and closing coils due to stuck mechanisms or poor transfer switches, ineffective switching of auxiliary switches, as well as faults in operating power supplies, closing contactors, microswitches, etc.

(2) Breaking and closing faults. This type of fault is caused by the circuit breaker body, and for low oil circuit breakers, it mainly manifests as fuel injection short circuit, arc extinguishing chamber burning loss, insufficient breaking capacity, and explosion when closed. For vacuum circuit breakers, it manifests as air leakage in the arc extinguishing chamber and bellows, reduced vacuum, and reignition of the capacitor bank. Cracking of ceramic pipes, etc.

(3) Current carrying fault. This type of fault is mainly caused by poor contact of the isolation plug in the switchgear, which leads to contact melting;

(4) Insulation fault. This mainly includes inter phase or phase to ground short circuit of the busbar, discharge between the busbar and the bushing, discharge of dynamic and static contacts, and hidden danger discharge in the cable compartment. The typical types of faults are external insulation to ground flashover, internal insulation to ground flashover, inter phase insulation flashover, lightning overvoltage flashover, porcelain bushing, capacitor bushing flashover, pollution flashover, breakdown, explosion, lifting rod flashover, CT explosion, breakdown, flashover, Broken porcelain bottles, etc.

(5) External forces and other faults. Including impacts from external objects, natural disasters, short circuits caused by animals, etc

The common types of faults in the ring network cabinet include: cable overlap fault, support insulator and busbar pile head discharge, gas chamber fault, etc.

1. PT and CT faults. The ring network cabinet with distribution automation interface is often equipped with PT and CT to provide data information such as operating power supply for switches and load current required for distribution automation.

2. Lightning arrester failure: Some lightning arresters in the ring network cabinet have broken down or exploded, causing a short circuit between phases in the cable room or discharge from the cable head to the shell.

3. Cable overlap fault:

(1) At present, the cable fixation method is sleeve type, which cannot achieve substantial fixation. During operation, the stress generated by its own weight, electric power, external forces, etc. will be transmitted from each phase to the sleeve where the cable is overlapped. In severe cases, it can cause damage and air leakage at the sleeve, leading to faults.

(2) Stress release: Before fixing the cable, it is often necessary to apply external force to twist the cable. After installation, the internal stress generated by the torsion is gradually released, and the resulting torque acts on the sleeve of the cable overlap.

(3) Load mutation: Due to load mutation, overvoltage, etc., the temperature of the cable head increases and the insulation sleeve bursts.

4. Discharge fault at the cable support insulator and busbar pile head. The cable room support insulator or busbar pile head may experience surface discharge or even breakdown due to exposure to dust, humidity, and other environments.

5. Secondary circuit fault: After a short circuit fault occurred in the system, the switchgear did not trip normally, resulting in a prolonged short-circuit current. The high current on the secondary side of the current transformer caused the insulation of the winding to burn out.

6. Protection fault: The protection control power supply is connected from the secondary of the voltage transformer. When a short circuit fault occurs, the secondary fault current of the CT will alarm. However, the short circuit fault causes a significant decrease in system voltage, making it impossible to trip the load switch. The short circuit current continues until the superior protection trips and cuts off the power supply.

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Datasheet
1.1 710-512-01-MVS1 Main Substation
Incoming Switchgear A01 B01 2
No Components Specification Unit Qty Maker
1 VCB
HVX12-50-31-F 275mm
Altitude ≤2000m
Opening voltage DC220V
Closing voltage DC220V
Energy storage voltage DC220V
Set 1 China
2 VT JDZ-10 10KV/√3/0.1KV/√3 Set 3 China
3 CT
LZZBJ9-12 3000/1A 5P20 10VA
5P20 5VA 5Fs5 5VA
Set 3 China
4 High voltage fuse XRNP1-12 0.5A Pc 3 China
5 Lightning arrester HY5WZ-17/50 Set 3 China
6 Intelligent control panel WY-9008A Pc 1 China
7 Short circuit and ground fault indicator EKL-4-1 Pc 1 China
8 Multifunctional electric instrument PD666-3S3 380V 5A Pc 1 China
9 Primary harmonic eliminator LXQ-12KV Pc 1 Fengyuan
10 Charged display DXN-12Q Pc 1 China
11 Temperature and humidity controller WY-CS-III Pc 1 China
12 Connecting piece JY-2 Pc 3 China
13 Junction box PJ1 Pc 1 China
14 Metering bracket Universal type Pc 1 China
15 Signal lamp ND16-22D/4 AC380V red Pc 1 CHNT
16 Signal lamp ND16-22D/4 AC380V green Pc 1 CHNT
17 Signal lamp ND16-22D/4 AC380V white Pc 1 CHNT
18 AC miniature circuit breaker NB1-63/2P C6A 6kA(R) Pc 2 Fengyuan
19 AC miniature circuit breaker NB1-63/3P C3A 6kA(R) Pc 1 Fengyuan
20 DC miniature circuit breaker NB1Z-63 2P C6 Pc 1 Fengyuan
21 AC miniature circuit breaker NB1-63/3P B2A 6kA(R) Pc 1 China
22 Universal test terminal RURTK/S Pc 30 China
23 Universal terminal block RUK 5B Pc 18 China
24 Cabinet top small bus Ø 6 copper bar m 11 Fengyuan

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