I.Overview of ABB vacuum circuit breaker VD4
The arc extinguishing chamber in the vacuum circuit breaker is integrally cast into the pole, so the structure will be firmer, which can provide sufficient protection for the vacuum interrupting chamber, and at the same time eliminate dust and moisture on the arc extinguishing chamber. The impact of the external insulation capacity. ABB vacuum circuit breaker VD4 arc extinguishing chamber permanently seals the main contacts of the switch into the vacuum environment, thus forming a breaking arc extinguishing unit.
In addition, the vacuum circuit breaker does not need any arc extinguishing or insulating medium. In fact, it is impossible for substances that are easily ionized in the arc extinguishing chamber. This phenomenon can be called opening in a vacuum. cut off the current. In any event when separation of the contacts occurs, the arc path between the contacts consists solely of the metal vapor of the contact material.
The generated arc phenomenon can only be maintained by external energy. When the main circuit current returns to the zero-crossing point in the natural state and is eliminated, then the arc cannot continue to be maintained. At this moment, the rapidly decreasing current-carrying density and the rapidly condensed vacuum metal vapor will prompt the rapid restoration of the insulation state between the contacts of the ABB vacuum circuit breaker VD4. Therefore, the vacuum interrupter also restores the insulating ability and the ability to withstand the transient recovery voltage of the system, and finally the arc that occurs can be extinguished.
Even at a small distance, the vacuum has a high dielectric strength, and it only needs to separate the contacts within a few milliseconds of the current zero-crossing point to ensure a successful breaking action. The contacts used in ABB circuit breakers are designed with special geometric shapes and materials, and have the characteristics of short-term arcing, low arc voltage, and low degree of ablation, thus ensuring the entire service life of the arc chute.
- Installation method: The circuit breaker operating mechanism adopts a frontal arrangement, which can be divided into two installation methods, including fixed type and withdrawable type.
- Application: Mainly used in power distribution system, and can control and protect equipment and lines such as cables, capacitor banks, transformers, generators, overhead lines and motors.
- Compliance with standards: GB/T1984, IEC62271-100 and other relevant standards of major industrialized countries.
- Safe operation: ABB vacuum circuit breaker VD4 has relatively complete mechanical and electrical locking functions, and can also cooperate with appropriate switch cabinets to complete complete power distribution. The locking mechanism can effectively prevent incorrect operation, and the key and padlock device can ensure the correctness of opening and closing operations and rocking in and out operations.
II.ABB vacuum circuit breaker VD4 structure description
The circuit breaker structure is composed of spring energy storage, free tripping, modular mechanical operating mechanism and other accessories. The operating mechanism is fixed to a metal shell with the pole (that is, the fixed ABB vacuum circuit breaker). device housing), the compact design ensures robustness and mechanical reliability. In addition to isolating contacts and air plugs with hoses connected to auxiliary circuits, withdrawable ABB vacuum circuit breakers are also equipped with a trolley chassis, which enables rocking-in and rocking-out operations when the switchgear door is closed.
●The structure of the integral cast pole of ABB vacuum circuit breaker VD4 is shown in the figure below, which needs to correspond to the corresponding serial number parameters:
- On the outlet end;
- Vacuum interrupter;
- Pouring the pole shell;
- Move the wire rod;
- Downstream end;
- Soft connection;
- Contact pressure spring;
- Insulation rod;
- Pole fixing inserts;
- The connection of the operating mechanism.
Casting pole features: The use of vacuum disconnection technology can prevent the contacts in the vacuum environment from being oxidized and polluted, and at the same time, the vacuum interrupter can be reliably protected and prevented from mechanical impact, dust, moisture and other potential accidents. Both fixed and withdrawable types can be installed and are suitable for different climatic conditions.
- The structure of ABB vacuum circuit breaker VD4 vacuum interrupter is shown in the figure below, which needs to correspond to the corresponding serial number parameters:
- Outlet rod;
- Twist protection ring;
- Corrugated pipe;
- End cover;
- Shield cover;
- Ceramic insulating shell;
- Shield cover;
- Contact;
- Outlet rod;
- End caps.
The breaking principle of ABB vacuum circuit breaker VD4 arc extinguishing chamber : the vacuum arc will be generated with the separation action of the current-carrying contact, and will continue until the current zero crosses the end of the arc, which can be affected by the magnetic field.
ABB vacuum circuit breaker VD4 has designed a complete series of secondary accessories to meet different installation and use requirements. At the same time, the operating mechanism also has a standard series of accessories and spare parts. These accessories can be installed through the front of the circuit breaker. The secondary control line The connection is made through a plug and socket. The operating mechanism is in the form of spring energy storage, and the standard configuration has a mechanical anti-jump device.
- The structure of the operating mechanism of ABB vacuum circuit breaker VD4 is shown in the figure below, which needs to correspond to the corresponding alphabetical serial number parameters:
A, Opening and closing auxiliary switch;
B, Energy storage motor;
C, built-in energy storage dry;
D, Mechanical indication of circuit breaker opening and closing
E, Counter
F, Plug-socket connection of electrical accessories;
G, energy storage status indication;
H, release, closing button;
L, opening button;
M, Closing and blocking electromagnet;
N, the second opening release;
O, Spring charged/unchafged signal contact.
III, ABB vacuum circuit breaker VD4 operating environment requirements
- Ambient air temperature: the highest value is +40°C, the average value within 24 hours is not greater than +35°C, and the lowest value (indoor) is -15°C.
- The altitude is less than or equal to 1000 meters, because the insulation performance of the air will decrease with the increase of the altitude, so when using the vacuum circuit breaker in the high altitude environment, the influence of the external insulation of the switch should be considered first.
- Seismic performance: The seismic intensity cannot exceed 8.
- It is suitable for use in humid tropical climates. The important parts inside the ABB vacuum circuit breaker VD4 are specially treated to withstand the environmental erosion of Class C specified in the UNI3564-65 standard.
IV, ABB vacuum circuit breaker VD4 anti-jump device description
Only the EL-type operating mechanism in VD4 is equipped with a mechanical anti-jump device, the main function is to prevent the circuit breaker from closing again under continuous mechanical or electrical commands. When a closing and opening command (whether remote or local) is received at the same time, there will be continuous anti-combination.
The ABB vacuum circuit breaker anti-jump VD4 is to ensure that when a closing operation is followed by an opening operation, the previous closing command will not cause the second closing operation, which can effectively prevent unfavorable work. situation occurs. If you want to perform the second closing operation, you need to let the previous closing command disappear first and then re-issue it.
In addition, ABB vacuum circuit breaker VD4 anti-jump device can be closed only when these conditions are met: 1. The operating mechanism has been fully stored; 2. The opening button is not pressed or the opening release (-MO1/ -MO2) does not start; 3. The circuit breaker is in the open state.
