An electromagnetic starter is a kind of contactor. It is used to convert significant loads. The main application is the activation, deactivation and reversal of asynchronous three-phase power units.
General information
The most significant parameter of an electromagnetic starter is its weight and overall dimensions. The product scores fairly well in this section as it requires design to withstand extreme loads.
In these products, powerful contact systems with arc chutes are used, which also affect the increase in dimensions. Despite this, devices can have the same operating current, but differ in weight and size. Contactors are made in open form. In this regard, the devices must be installed in lockable cabinets or compartments, protected from dirt, foreign matter and dirt.
Application
Due to unpretentiousness and ease of maintenance, the electromagnetic starter (220 volts) is widely used to control various industrial and householdnodes (machines, furnaces, ventilation systems, etc.). The scope of application is almost limitless, from escalators and elevators to serious industrial systems.
The device in question will protect the machine or installation from erroneous start. The units block the power supply if an interruption or overheating of the unit is planned. In addition, the electromagnetic starter protects against abnormal overloads that can disable the entire system.
Varieties
By types, electromagnetic starters differ in the following parameters:
- Regular versions that energize the starter and then pull the core with contacts. As a result, normally closed elements are switched off, and ordinary ones - when power is supplied to the electromagnetic starter. An electromagnet attracts a metal core with contacts attached to it. In this case, normally closed ends open, and open ends close. When the power is turned off, the process is played in reverse order.
- Reverse modifications. These units are reversers with electromagnets, which have a similar base and connections for blockers. This design makes it possible to avoid the simultaneous activation of two devices.
According to the type of connection, the PML electromagnetic starter is divided into categories: AC-1, AC-3 and AC-4. Between themselves, they differ in the voltage consumed and the type of connection.
For example, AC-1 is inductive orlow active load, AC-3 - direct start with squirrel-cage rotor, AC-4 - a similar system with the possibility of braking and switching off by current reverse application.
Features
220 V electromagnetic starters, depending on equipment and additional options, are divided into three main groups:
- Open options with a degree of protection of at least "IP-00". They are operated when placed in protected containers, cabinets and other boxes, protected from moisture and dust.
- Protected models. They have a degree of protection of the order of IP-40, are used in light dust.
- Instruments with IP-54 protection level do not let in moisture and dust, can be used outdoors, not just indoors.
Versatility
The connection of the electromagnetic starter is carried out by means of signal contacts that provide the moment of "sticking". For example, after a short press of the "Start" key, the ends of the starter are closed. By briefly holding the indicated button, the contacts are disconnected and remain in a neutral position until they are switched on again after the power supply is restored.
If the 380 V electromagnetic starter is started in reverse mode, it uses taps to block the second analogue, This prevents the possibility of a short circuit. A huge number of branches is useful for assembling sophisticated control systems, if necessary. These can be analogues with software correction,the possibility of increasing or reducing the load, as well as schemes with remote circulation. There is also a predisposition to introduce the number of contactors with additional blocks or skids with hooks.
PME electromagnetic starter
The thermal relay for the devices in question serves to protect against possible prolonged overload or violation of the integrity of the insulating layer. The working circuit has a special plate that opens the circuit at critical current parameters. The level of "conflict" is regulated within 15%. It follows from this that overload should be considered initially when developing a design project.
The following is not recommended:
- Install at the top of the unit mounting box (hot air mixture will accumulate there).
- Use fixtures in compartments with large temperature differences.
- Operate the device on a chassis subject to strong vibrations and mechanical stress.
- Use equipment above 150 A.
- Mount an electromagnetic starter (380 V) in places where the temperature exceeds 40 degrees Celsius.
Nuances
There are some nuances in the operation of the devices in question. They are related to the features of the application of starters. The operation is performed by supplying a countercurrent with an intensive increase in the load on the main contacts. As a result, it is desirable to initially set a margin of order 1 in the parameters,5-2 times.
In this segment, it does not hurt to mention analogues with a permanent magnet. They are designed for long-term operation without interruption, they are connected through a rectifier.
Maintenance and care
Maintenance of the electromagnetic starter PM-12, as well as its analogues, is practically not required until the working life of the device is completely exhausted. This is because the functional range is directly dependent on the opening/closing cycles. There may be several hundred thousand times when it comes to standard fixtures used in dry and ventilated rooms.
In the process of work, it is necessary to monitor the condition of the fixing elements. They must be constantly tightened, do not let moisture and dust through, and are made of appropriate materials. Contacts are cleaned very rarely, without unnecessary need, this procedure is best excluded from service altogether. This manipulation is indicated in case of strong melting, burning. Processing of details is carried out by means of a needle file with a fine-grained surface.
Operation
After prolonged use, the devices in question may emit increased and uncharacteristic sounds. If this moment transforms into regular rattling, the unit should be disassembled, the cause of the problem should be found and corrected. In addition, it will not be superfluous to check the coil and core. Before assembly, it is recommended to process the work items with a clean rag, and also checkknot for deformations and cracks.
Technical parameters
The durability of a non-reversing electromagnetic starter is determined by checking the mechanical stability of the working contacts. In almost any electromagnetic relay, the manufacturer indicates two types of warranty. The second parameter concerns electrical durability, which resists a working arc.
The switching capabilities of the device determine the possibility of switching on and the maximum current parameter, which allows not to violate the specifications for wear resistance specified in the instructions. For example, triggering 8 to 10 times per minute indicates a system malfunction.
Synchronous fuse deactivation indicates smooth contact operation and electrical durability. If the reaction fades at a certain point, this indicates the possibility of an arc forming, which welds the working group of devices, rendering them unusable. The specified parameter refers to the defining moments that affect all the main characteristics of the electromagnetic starter.
Power consumption can be redistributed to the switching and operation of the main relay. Features of thermal protection make it possible to preserve the integrity of the motor windings, preventing equipment failure.
Recommendations
If the device in question is used incorrectly, the difference in damage due to incorrect start-up can reach 30-40 percent (ifthere is an incorrect activation of the equipment). This moment is especially affected by vibration and bouncing of parts when the fading indicators are turned off at a certain amplitude. The higher the weight of the moving element, the lower the pressing force.
As a rule, the resulting arc goes out when the power plant is turned off. The moment of transition is usually fixed at zero. At a frequency of 50 Hz, this situation can occur no more than 100 times per second. As a result, the update procedure does not particularly affect the protective functionality of the unit. Silver contacts provide optimal performance.
Summarize
The characteristics and features of electromagnetic starters were discussed above. As can be seen from the review, the devices can operate with a voltage of 380 and 220 volts, as well as switch useful energy. It is recommended to choose the devices under consideration based on the final parameters and established tasks. There are modifications on the market that satisfy user requests for the activation of a single power unit or the automation of an entire production workshop.
