1. Commonly used mine electrical equipment
Commonly used mining electrical equipment includes vacuum switches, transformers, lighting signals and electric drill comprehensive protection devices.
Explosion-proof electrical equipment for mine
(1) Vacuum switch technology
Motors of 40kW and above should be controlled by a vacuum electromagnetic starter.
1. The structural characteristics of the vacuum switch tube
Vacuum interrupters are divided into vacuum interrupters for circuit breakers, vacuum interrupters for load switches, and vacuum interrupters for contactors according to their purpose, use occasions and breaking capacity.
Explosion-proof electrical equipment for mine
The vacuum switch tube is composed of a shielding cover, a bellows, a moving (static) contact, a moving (static) contact rod and other parts.
Commonly used vacuum switches include mine explosion-proof vacuum feed switches and mine explosion-proof vacuum magnetic starters.
2. Explosion-proof vacuum feed switch for mine
DKZB-400/1140 mine explosion-proof vacuum feed switch, mainly used in underground mines, rated voltage 1140V or 660V, frequency 50Hz power distribution system, as the main line switch or branch switch, the load of the controlled circuit The current is 400A.
Explosion-proof electrical equipment for mine
(1) Components: The feed switch is mainly composed of flameproof enclosure, vacuum circuit breaker, control circuit power switch, core board assembly, check switch, fault signal indicator, etc.
(2) Technical features: the rated voltage of the feeder switch is 1140V or 660V; the rated current is 400A; the maximum breaking capacity is 7500A; the breaking time is from the receipt of the leakage relay action signal to the completion of the breaking, the time is not more than 0.03s; opening and closing Rated current is 3000A. The switch can be connected to an external master switch to implement remote excitation.
(3) Protection performance:
① The overcurrent release has two protection features: long-time overload action and instantaneous short-circuit action. The overload protection setting current is 6 blocks from -400A to 160A, and the short circuit protection setting current is 6 blocks from 1200A to 4000A;
Explosion-proof electrical equipment for mine
②The switch has undervoltage trip coil, shunt trip coil and electronic overcurrent trip.
3. Flameproof vacuum magnetic starter for mine
Introduce the following two common explosion-proof vacuum magnetic starters for mines.
(1) BQD7-80 explosion-proof vacuum magnetic starter for mine
① Composition: The starter is a cylindrical flameproof enclosure with two junction boxes and a circular main cavity on the front to install electrical components. It is composed of a vacuum contactor, a current-limiting thermal relay, a leakage protection plug-in, a fuse, etc.
Explosion-proof electrical equipment for mine
②Technical characteristics: The rated voltage of the starter is 660/380V, and the rated current is 80A. When the voltage is 660V, the motor power is controlled to 55kW. The mechanical life is 1.5 to 4.6 million times. The ultimate breaking capacity of the vacuum contactor is 2500A, and the breaking capacity of the reversing isolating switch is 12600A.
③Protection performance: The starter has the functions of overload protection, phase failure protection, short circuit protection and leakage lockout.
(2) Flameproof vacuum electromagnetic starter for mine
① Composition: The starter is mainly composed of flameproof cable wiring cavity, drum-shaped flameproof main cavity, isolation switch handle, button, and low-voltage vacuum contactor, motor protector, transformer, fuse and other electrical components fixed on the rubber wood in the main cavity. .
Explosion-proof electrical equipment for mine
②Technical characteristics: The rated working voltage of the starter is 380V or 660V, the rated working current is 80A or 120A, and the control circuit voltage is 36V. When the voltage is 380V and 600V, the maximum power of the control motor is 65kW and 160kW respectively. The ultimate breaking capacity is 2500A, 3 times, and the breaking capacity of the commutation isolating switch is 320~360A, 3 times in both positive and negative directions.
④Protection performance: JDB-120G adopts overload protection, short circuit protection, phase failure protection and leakage lockout.
(2) Transformer
Transformers are electrical equipment used to change the AC voltage and current in an AC circuit.
1. Transformer classification and scope of application
Transformers are divided into power transformers and special transformers. Power transformers are divided into two types: oil-immersed or dry-type.
2. Structural features
The transformer is composed of iron core, winding, shell, voltage regulating switch, insulating sleeve, junction box, cooling system, bottom bracket, etc.
(3) Illumination signal and integrated protection device for electric drill
1. ZXZ8-2.5 (4) Ⅱ type mine explosion-proof lighting signal comprehensive protection device
The power supply of ZXZ8-2.5(4)Ⅱ mine explosion-proof lighting signal integrated protection device can be taken from 660V or 380V power supply system, and its output voltage of 127V can be used as lighting and signal load voltage, with short circuit, leakage protection and cable insulation monitoring And other comprehensive protection.
(1) The primary voltage of the main transformer is 660V or 380V, and the secondary output voltage is 127V. The rated capacity is 4 (2.5) kV·A, the rated current when the power supply voltage is 660V is 3.5 (2.19) A; the rated current when the power supply voltage is 380V is 6.1 (3.79) A; the rated current when the secondary voltage is 127V It is 17.4(10.85)A. The wiring method is Y-Δ/Δ type.
Explosion-proof electrical equipment for mine
(2) Within the protection range of the specified lighting signal cable length, when 4(2.5)kV·A is used as lighting, its rated current value is 20(12)A; when used as a signal, its rated current value is 5.5(4.5) A.
(3) The resistance value of leakage action is 2kΩ.
(4) The resistance value of the leakage blocking action is 2~4kΩ.
(5) The dangerous indication value of cable insulation monitoring is 13 (1±10%) kΩ.
(6) The fluctuation range of the power supply voltage is 10%.
2. BZ80-2.5Z type electric drill transformer comprehensive protection device
It has a power supply device with a capacity of 2.5kV?A or 4kV?A and a voltage of 127V; using a four-core cable, the pilot circuit can be used for remote operation, so that the electric drill does not run and the cable is not charged; it can be realized for the electric drill and its cable Overload and short circuit protection; It also has a leakage protection device of 127V system, and can achieve leakage self-locking and leakage lock. By changing the Y or Δ connection method on the primary side grounding of the main transformer, it can be universally used in 660V and 380V power grids.
2. Explosion-proof and prevention of explosion-proof electrical equipment
(1) The common explosion phenomenon of explosion-proof electrical equipment
The explosion-proof enclosure of electrical equipment loses its anti-explosion performance or explosion-proof performance (that is, non-explosion transmission), that is, the explosion is lost.
The common explosion phenomena of underground explosion-proof electrical equipment generally include the following:
(1) The flameproof enclosure is severely deformed or cracked, the weld seam is open, the connecting screw is incomplete, the screw is damaged, or the screwing depth is less than the specified value, causing the mechanical strength to fail to meet the requirements of explosion resistance and fail to explode.
(2) The flameproof joint surface is severely corroded. Due to mechanical damage, the gap exceeds the specified value, there are pits, and the connecting screws are not tightly pressed, etc., and the explosion fails to meet the requirements of non-detonation.
(3) The cable entry and exit ports do not use qualified sealing rubber ring or no sealing rubber ring at all; the unused cable connection hole does not use qualified sealing baffle or does not have any sealing baffle at all, which may cause the failure of explosion.
(4) Randomly add electrical components in the equipment enclosure to make certain electrical distances less than the specified value, or the insulation is damaged, and the arc extinguishing device fails, resulting in a short circuit between the phases through the enclosure arc and grounding, causing the enclosure to be short-circuited, arc burned and lost .
(5) The two explosion-proof chambers in the shell are connected due to the burning of the terminal and the wiring tube. When the internal explosion occurs, a pressure superimposition is formed, which causes the shell to fail to explode.
(2) Reasons for the failure of explosion-proof electrical equipment
(1) Improper maintenance and overhaul of electrical equipment causes the protective layer to fall off, causing debris such as mineral dust on the explosion-proof surface, and pits will appear on the fastening mating joint surface, which may increase the gap between the explosion-proof joint surface.
(2) A partial roof fall in the well may damage the shell of the explosion-proof electrical equipment. Improper movement and relocation may cause shell deformation and mechanical damage, which can cause the explosion-proof electrical equipment to fail.
(3) Due to unfamiliarity with the performance of the equipment, no special tools were used or misoperation occurred during the loading and unloading process.
(4) For the explosion-proof surface fastened with screws, the parts cannot be fastened well due to the shallow depth of the screw holes or the too long screws, so that the explosion-proof surface will have a gap and fail to explode.
(5) Due to the staff's insufficient knowledge of explosion-proof theory, the failure to implement various regulations normally, and the carelessness of the equipment's explosion-proof requirements, it may cause explosions.
