Lw8a-40.5 Porcelain Column

I. Product Overview:

Model 1 LW8-40.5 outdoor high-voltage sulfur hexafluoride circuit breaker is an outdoor high-voltage electrical equipment with sulfur hexafluoride as arc extinguishing medium and three-phase alternating current of 50 Hz. It is suitable for the control and protection of 35kV transmission and distribution system. It can also be used for connecting circuit breakers and switching capacitor banks. It can also be equipped with current transformers for measurement and protection.

This circuit breaker meets the requirements of national standard GB 1984-1989 "AC High Voltage Circuit Breaker" and IEC 60056:1987 "High Voltage AC Circuit Breaker".

Model 3 LW8-40.5 circuit breaker is equipped with CT14 spring operating mechanism.

2. Main characteristics of circuit breakers:

1. Excellent interruption performance, short arcing time and long electrical life. Under 100% rated short-circuit interruption current, 16 times of interruption are not repaired and sulfur hexafluoride gas is not replaced.

2. The mechanism has high reliability, strong closing ability and can operate frequently.

3. Open and close capacitor bank current 400 A without reburning;

4. No reburning of 50 km long cut line;

5. It has simple structure, small volume and long maintenance period.

3. Product use environment:

1 Altitude: not more than 2000 meters;

2. Environmental temperature: upper limit 40 C, lower limit - 30 C;

3. Air pollution degree: Grade III;

4. Wind speed: not more than 34m/s;

The intensity of the earthquake does not exceed 8 degrees.

5. The structure and working principle of circuit breaker:

1 General layout

LW8-40.5 type circuit breaker belongs to tank type sulfur hexafluoride circuit breaker. It adopts three-phase separated floor tank structure. Three-phase arc extinguishing chamber is installed in three grounded metal enclosures respectively. The overall arrangement is shown in Figure 1 or Figure 2 (mechanism side). Three-phase sulfur hexafluoride gas is connected through copper tube to keep the pressure of three-phase sulfur hexafluoride gas consistent. Pressure is measured by a special density meter for sulfur hexafluoride gas mounted on a chassis.

The three-phase circuit breaker is mounted on a chassis welded with angle steel. The upper, sides and end of the chassis are equipped with sealing plates, which can effectively block the transmission part of the circuit breaker directly impacted by flying rocks and wind sand outdoors, and enhance the reliability of the circuit breaker operation. The other end of the chassis is equipped with CT14 spring operating mechanism, through transmission. The three-phase linkage operation is realized by the axle and the tie rod.

The main components of circuit breaker are: outlet cap, hollow ceramic sleeve, arc extinguishing chamber, adsorber, current transformer assembly, transmission box, connecting rod, chassis, CT14 spring operating mechanism.

2. Action Principle of Drive System

Fig. 3 is a schematic diagram of one-phase drive system of LW8-40.5 circuit breaker. O1 and O2 are two fixed rotating shafts. O1A, AB, O2 B, O1, O2 constitute a set of four-bar linkage mechanism, and O2 C, CD and movable contacts constitute a set of rocker slider mechanism, which can make the movable contacts move up and down in a straight line.

When closing, the spring mechanism output shaft active arm O1A rotates around the O1 axis, the rotation angle is about 57.3 degrees, and the driving arm 02B rotates around the O2, the rotation angle is 60 degrees. This four-bar mechanism drives the arm O2 C to rotate around the O2, and the rotation angle is also 60 degrees. Drive rocker CD, CD drive contact upward for linear motion, travel is about 95 mm. Opening is the reverse motion of closing.

3. Pressure (Density) Monitoring of Sulfur Hexafluoride Gas

The pressure (density) of sulfur hexafluoride gas in circuit breaker is monitored by a special sulfur hexafluoride density controller with temperature compensation function. When the sulfur hexafluoride gas pressure of circuit breaker drops to 0.42 MPa, an electrical contact of density controller is connected, and the circuit breaker sends out an alarm signal. At this time, the circuit breaker should be supplied with air to the rated gas pressure (0.45 MPa). When the sulfur hexafluoride gas pressure of the circuit breaker continues to drop to 0.4 MPa, that is, the minimum functional pressure of the circuit breaker, another electrical contact of the density controller is connected. At this time, according to the needs of the system, by changing the circuit breaker wiring (see figure 8 (a) wiring schematic diagram), three different control and protection schemes can be provided for users. Scheme 1: Connector (switch terminal) XB1 and XB2 are connected. When the sulfur hexafluoride gas pressure of the circuit breaker drops to 0.4 MPa of the minimum function pressure, the circuit breaker is forced to open and the closing circuit is blocked. Scheme 2: Connector XB1 is disconnected and XB2 is connected. When the pressure of sulfur hexafluoride gas in the circuit breaker drops to 0.4 MPa, the closing circuit is blocked, but it can be switched off remotely or in situ. Scheme 3: Connector XB1 or XB2 are disconnected. When the pressure of sulfur hexafluoride gas in the circuit breaker drops to 0.4 MPa, the opening and closing circuits are blocked at the same time, and the circuit breaker can not operate.

4 Hollow Porcelain Cover

The structure of the porcelain sleeve is shown in Figure 4. It consists of porcelain pieces and upper and lower flanges. The bending test damage value of the porcelain sleeve is > 1.7X104N; the hydraulic test damage value is > 3.5X106 Pa; the routine hydraulic test value is > 2.0X106 Pa; and the creepage ratio is 26 mm/kV. Porcelain sheath acts as insulation and supporting arc extinguishing chamber.

5 Contact System

The contact system of LW8-40.5 circuit breaker consists of moving contact and static contact.

The structure of the movable contact mainly consists of insulator, shielding ring, contact support, tie rod, cylinder, nozzle, movable arc contact, strip contact, oil-free bearing, pressure plate and screw.

The structure of static contacts is mainly composed of insulators, static contacts, cooling chambers, tubes, joints, finger-shaped contacts, static arc contacts and connecting screws.

The contact form of the dynamic and static contacts is insertion type, and the current-through contacts and the arc contacts are separated. When opening, the current-through contacts are disconnected first, and the arc is generated between the dynamic and static arc contacts. When closing, the dynamic and static arc contacts are contacted first, and the breakdown occurs between the dynamic and static arc contacts when closing. Therefore, when the circuit breaker divides or closes the rated current or fault current, there will be no arc between the current-passing contacts, which can ensure the good contact between the dynamic and static contacts and the stability of the circuit resistance when moving, thus ensuring the stability of the circuit resistance. The stability of long-term operation of circuit breaker and the cumulative number of times of breaking current are high. The circuit breaker can be operated for a long time without the need to repair the contact system.

6. The structure of arc extinguishing chamber is shown in Fig. 5. It is mainly composed of large shell, moving contact, static contact, transmission box, self-sealing valve, sealing ring, connecting bolt and other components. All arc extinguishing components are installed in large shell. The large shell is made of cast aluminium alloy, which is strong and light in weight. Pressure tests are carried out on large enclosures before assembly. Hydraulic test: Damage test value is 2.1X106 Pa (sampling test 5%, large shell after damage test can not be re-assembled); Routine test value is 9.0X105Pa. Pressure test: 6X105Pa, no

There must be air leakage. Leakage rate is less than 1X10-6cm3/s.

The arc extinguishing chamber of LW8-40.5 circuit breaker has a single pressure and pressure structure. The arc extinguishing does not depend on the arc energy.

Therefore, the arc can be reliably extinguished within 6-18 MS for both large and small currents.

It is a short arc circuit breaker.

The arc extinguishing process of LW8-40.5 is shown in Fig. 6. When the circuit breaker is in the state of closing and ready to switch off, the current-through contacts and arc contacts are closed. In the process of opening, the movable cylinder moves relative to the static contactor and the air in the cylinder.