Switch mmo 110 1250 bulgaria factory name. Electrical networks, equipment, documentation, instructions. Factors considered for a good grounding system

2.1 Familiarize yourself with the design of overhead power lines.

2.2 Study the types and designs of insulators, make sketches of pin insulators used on overhead lines -0.38 kV and above.

2.3 Study the types and designs of pins and hooks for overhead lines - 038 kV, make their sketches for overhead lines - 0.38 kV.

2.4 Study the designs, types and purpose of clamps, coupling fittings for hanging garlands on overhead line supports, make sketches of clamps, staples, earrings and connectors.

2.5 Study the rules of operation, maintenance and repair of overhead lines.

3 Security questions

3.1 What is the design of linear fittings for overhead lines - 0.38 kV.

3.2 What is the design of linear fittings for overhead lines above 1 kV.

3.3 What is the design of insulators for overhead lines - 0.38 kV.

3.4 What is the design of insulators for overhead lines above 1 kV.

3.5 How the 0.38 kV overhead line is operated.

3.6 How to operate overhead lines above 1 kV.

3.7 How it is produced Maintenance Overhead line – 0.38 kV.

3.8 How routine repairs of overhead lines above 1 kV are carried out.

Laboratory work No. 3

Operation of high voltage type circuit breaker

MMO 110/1250/20 U1

Purpose of the work: to study the purpose and operating conditions of the MMO 110/1250/20 U1 switch; the process of extinguishing the arc in circuit breakers and the design of the arc extinguishing device; study the maintenance procedure during operation of the MMO 110/1250/20 U1 circuit breaker.

1 Theoretical explanations

1.1 Purpose

A small-volume circuit breaker type MMO 110/1250/20 U1 with one spring-motor drive ZPM 70000 is designed for operational and emergency switching on and off of part of the power distribution network. It can be installed in open switchgears and is designed to operate in temperate climates with the following climatic parameters:

Ambient air temperature is not higher than plus 40°C (with an average daily temperature not higher than plus 35°C) and not lower:

a) minus 40°С (occasionally minus 45°С) for switches filled with ATM -65 transformer oil according to TU 33-1 -225 -69.

b) minus 25С for switches filled with transformer oil in accordance with GOST 982-68.

1.2.2 Relative air humidity - up to 100%.

1.2.3 Altitude above sea level - up to 1000 m.

Normal operation of the switch is not guaranteed:

– in an environment with big amount conductive vapors or dust, which may cause big pollution isolation;

– in an environment containing chemically aggressive gases;

– in close proximity to explosive and fire hazardous objects;

– in places where the switch will be subject to industrial vibrations, shocks, etc.;

– if the instructions in these instructions are not followed.

The full type designation of the MMO 110/1250/20 U4 circuit breaker is deciphered as follows: MMO - symbol series, 110 – rated voltage in kilovolts, 1250 – rated current in amperes, 20 – rated shutdown current in kiloamperes, U – for areas with a temperate climate, 1 – placement category: for outdoor installation.

The designation of the spring drive of the ZPM 70000 circuit breaker is deciphered as follows: ZPM is the symbol of the drive, 70000 is the average potential energy of the switching springs in the wound-up state, kg cm. The technical data of the switch is given in table. 8.

Table 8 – Technical data of switch type MMO 110/1250/20 U1

The insulation of the elements of the control, blocking and signaling circuits of the drive (without an electric motor) can withstand a test voltage of industrial frequency equal to 2 kV for 1 minute. The switch is suitable for operation in icy conditions with an ice crust thickness of up to 20 mm and wind speeds of up to 15 m/s; in the absence of ice and wind speeds up to 40 m/s. The switch is designed for a wire tension (in the horizontal direction in the plane of the pole) equal to 100 kg·s.

The switch has the following reliability and durability indicators:

a) mechanical life of 1000 starts and 1000 shutdowns;

b) switching life - the number of total on and off operations permissible without inspection and repair of the circuit breaker:

– rated breaking current of 3 operations;

– 60 % rated current shutdowns – 20 operations;

c) overhaul period is 3 years.

The contact leads are made of aluminum with coated (silver) contact surfaces.

The MMO 110/1250/20 type circuit breaker belongs to liquid high-voltage circuit breakers with a small volume of arc-extinguishing fluid (transformer oil).

The principle of operation of the switch is based on extinguishing the electric arc that occurs when the contacts are opened by the flow of a gas-oil mixture formed as a result of the intensive decomposition of transformer oil under the influence of the high temperature of the arc. This flow receives directional movement in an arc extinguishing device located in the arc burning zone.

The switch is controlled by a spring drive. Operational activation occurs due to the energy of the drive's activation springs, and deactivation occurs due to the energy of the tripping springs of the switch itself, which are triggered by the action of the tripping electromagnet on the drive latch, which holds the switch in the on position.

The switch consists (Figure 3.1) of three poles 5, a spring-motor mechanism 11, connected by means of a connecting rod 14 placed in protective connecting pipes 13.

Pole design and operation

The switch pole consists of an insulating wire column 8 and two breaks (Figure 3.1). The insulating drive column (Figure 3.2) consists of a lower crankcase 3, on which a disconnecting spring 5 is mounted. The insulator 6 connects the crankcase with the upper crankcase 9 and ensures isolation of breaks in relation to the ground. An insulating drive shaft 7 with an upper lever 12 and a lower lever 4 is placed in the insulator. The insulating drive shaft 7 transforms the translational motion of the drive mechanism into a rotational motion and transmits it to breaks.

The internal space of the insulator is filled with transformer oil, plug 8 on the upper crankcase is used to add oil, tap 1 is used to release oil on the lower crankcase. The oil level can be monitored using the oil indicator 10. The lower crankcase has 4 holes with a diameter of 22 mm for connecting the pole to the foundation, and the upper crankcase has 8 holes M 16 - for connecting breaks.

The lower lever has two rods 13, which are connected to the break levers 14 (Figure 3.3).

The pole break (Figure 3.3) consists of an expansion chamber 4, an arc-extinguishing chamber with an upper contact 8, a housing 15, connected to the upper terminal 6 through an insulating cylinder 9 and an insulator 10.

The expansion chamber accumulates gases released during the arc extinguishing process and, when a certain pressure is reached, releases them through gas vent valve 1 (Figure 3.3). It is equipped with valve 2 (Figure 3.1), designed to regulate the oil level in the rupture and fill the rupture with gas to a certain pressure, and an oil indicator 1 with a pressure gauge (Figure 3.1), indicating the presence of the required amount of oil in the rupture. The pressure in the expansion chamber is controlled by the readings of the pressure gauge.

The gas vent valve (Figure 3.5) has the following action: spring 16, through guide 13, presses membrane 12 to the sealing surface of cover 10. The volume enclosed by membrane 12 and cover 10 covering the sealing surface is filled with oil from reservoir 9. In this position, the cover is closed and provides tightness of the expansion chamber.

The pressure in the expansion chamber through the hole in the special nut 1 acts on the oil in the valve. When the pressure in the expansion chamber increases as a result of commutation above the pressure to which the valve is set, the membrane 12 with guide 13 moves to the left and the valve opens. Through the hole in the guide 13, the oil is pushed out from the volume of the cover 10 and pipe 13 to the outside, after which the release of gases from the expansion chamber begins. The valve closes at a lower pressure, since after its opening the pressure begins to act on the central part of the membrane surface, limited by the sealing surface of the lid.

After opening the valve, ball 6 does not allow oil to flow out of the reservoir. After closing the valve, the ball returns to its original state and the valve is filled with oil again.

The presence of continuous high pressure in the tanks improves the operation of the circuit breaker when disconnecting unloaded lines, increases the wear resistance of contacts, oil and arc-extinguishing chamber when disconnecting load currents, helps maintain a high level of internal insulation and its independence from external conditions. Pipe 20 protects the valve from water ingress.

The arc extinguishing device (Figure 3.4) with an upper contact consists of a holder 1, to which is mounted an upper contact 2, a glass epoxy cylinder 9, in which insulating partitions 7 are placed, tightened with a nut 10 and the holder using a spacer cylinder 6.

A transmission mechanism is placed in the crankcase 15 (Figure 3.3), which transforms the rotational movement of the insulating drive column into the translational movement of the movable contact 12. The lower socket contact 16 is mounted to the crankcase. The gap is equipped with a valve 13 for topping up, draining and taking oil samples.

The current-carrying path of the break is as follows: arc extinguishing device holder 5, upper contact 7, moving contact 12, lower contact 16, housing 15, contact surfaces B to the second break, pin 6.

Switching the pole on and off is carried out in the following way.

The translational motion of the drive mechanism is transformed by the shaft of the insulating drive column into a rotating one, transmitted to the breaks, where it is converted into the translational motion of the moving contact.

The switching operation is ensured by the coil springs 8 (Figure 3.2) of the drive mechanism, and the switching operation is ensured by the switch springs 5 ​​(Figure 3.2).

The electrical wear resistance of the moving and upper contacts is quite high due to the use of metal-ceramic elements - respectively, tip 11 (Figure 3.3) and guard ring 11 (Figure 3.4).

Figure 3.2 – Insulating drive column:

1 – tap; 2 – foundation holes 4 x  22; 3 – lower crankcase; 4 – lower

lever arm; 5 – deflection spring; 6 – insulator; 7 – insulating drive

shaft; 8 – plug; 9 – upper crankcase; 10 – oil indicator; 11 – remote insert; 12 – upper growl; 13 – rod; 14 – washer; 15 – M12 bolt; 16 – 16 M16 holes for breaks

Figure 3.3 – Gap:

1 – gas vent valve; 2 – reservoir; 3 – tube for filling the tank; 4 – expansion chamber; 5 – arc extinguishing device holder;

6 – upper terminal; 7 – upper contact; 8 – arc extinguishing device;

9 – insulating cylinder; 10 – insulator; 11 – tip; 12 – moving contact; 13 – oil tap; 14 – lever; 15 – crankcase; 16 – lower contact; 17 – bolt

Figure 3.4 – Arc extinguishing device with top contact:

1 – holder; 2 – upper contact; 3 – finger; 4 – cylinder; 5 – guarded ring; 6 – remote cylinder; 7 – insulating washers; 8 – spacers; 9 – cylinder; 10 – nut; 11 – valve

Figure 3.5 – Gas vent valve:

1 – nozzle; 2 – seal; 3 – seal; 4 – cap; 5 – pipe; 6 – ball; 7 – spring pin; 8 – valve; 9 – reservoir; 10 – cover; 11 – nut; 12 – membrane; 13 – guide; 14 – bolt; 15 – spring washer 1; 16 – spring; 17 – body; 18 – tube; 19 – nut; 20 – pipe; 21 – transformer oil.

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