VA switches are switching devices that are used to turn on /off the electrical circuit in order to protect electrical devices, cables from increased current overloads and short circuits in the network. They are often used in large metallurgical enterprises. They perform the following functions:
- Electrical circuit commutation;
- Protection against overload currents by disconnecting the electrical circuit at the moment of current flow that exceeds the permissible rating;
- Disconnects from the network the circuit intended for protection at the moment of occurrence of limiting currents and short circuits
The VA low-voltage circuit breaker is one of the modern representatives of those outdated devices. By the way, the design of modern mechanisms was patented in 1924. So, the VA series circuit breaker is designed to open the network in such cases:
- unstable voltage;
- short circuits;
- infrequent online outages.
VA switches are installed in control systems, in special boards or panels. They are good because they work instantly. Devices can be classified according to the type of release (main disconnecting element). Today there are thermal, electromagnetic and combined automatic devices. Thermal VA - in them a bimetallic plate is installed as a release. At high voltage or short circuit, it heats up and the network is disconnected. Also, such plates are suitable in cases where the network is regularly unstable. But the voltage fluctuations are not great. Electromagnetic circuit breakers with a coil inside have proven themselves to be durable in operation. The coil is designed for enormous mechanical durability (2 million VO cycles). Simple operation, easy installation, instant response and low price - these are the advantages of these switches. Switching devices help to save expensive equipment. Combo models combine both a plate and a coil. You can also distinguish VA by the presence of a protective cover. Models with a plastic housing are dust-resistant, but not moisture-resistant. These machines have a degree of protection IP20. The first number indicates the diameter of the abrasive particles. The second is for resistance to moisture. "0" means there is no moisture protection. Open circuit breakers have IP00 design.
Main technical (operating) characteristics for VA switches
Switches are suitable for AC max. 690V /50 Hz. When operating in a network with direct current up to 440 V at a current (Inom) from 16 to 1000 A. According to the requirements of GOST, the number of poles in VA machines is 3. Depending on the model, some indicators differ. Climatic design of devices according to GOST 15150-69 - UHL , location category - 3. Installation work of the machines is carried out at an altitude of no more than 2000 meters above sea level. The vibration frequency range should not exceed 35 Hz. The level of environmental pollution of the working environment for automatic machines VA "3". DIN rail mounting is possible. The range of switches is presented in the form of 10 models. They all have their own characteristics and differences. For example, VA04-36 is interchangeable with another automatic machine of the same VA57-35 series. VA51-35 is a circuit breaker for installation in cabinets, since there is no protective case. This is an analogue of the outdated BA04-36 circuit breaker. To work in conditions of consistently high temperatures (+40 degrees and above), it is recommended to buy the VA51-39. What to look for when buying YOU machines The easiest and most reliable way to replace devices is to buy a similar model. Today it is still possible to find warehouse illiquid assets in excellent condition. However, in this case, you do not receive any warranty for the product. Naturally, it is better to order devices in trusted stores or via the Internet. There are not so many manufacturers of quality switches. Pay attention to markings, machine parameters, mains voltage.
What to look for when buying VA vending machines
The easiest and most reliable way to replace devices is to buy a similar model. Today you can still find stock in excellent condition. However, in this case, you do not receive any warranty for the product. Naturally, it is better to order devices in trusted stores or via the Internet. There are not so many manufacturers of quality switches. Pay attention to markings, machine parameters, mains voltage.