The electromagnetic starter is a type of contactor. It is used to convert significant loads. The main application is the activation, shutdown and reversal of asynchronous three-phase power units.
general information
The most significant parameter of the electromagnetic starter is the mass and overall dimensions. The product has a rather high performance in this section, since withstanding extreme loads requires appropriate design.
The indicated products use powerful contact systems with arcing compartments, which also affect the increase in size. Despite this, the devices can have the same operating current, but differ in mass and size. Contactors are made in the clear. In this regard, the devices must be installed in lockable cabinets or compartments protected from ingress of dirt, foreign matter and dirt.
Application
Due to its unpretentiousness and ease of maintenance, an electromagnetic starter (220 volts) is widely used to control various industrial and economic units (machines, furnaces, ventilation systems, etc.). The scope is almost limitless, from escalators and elevators to serious production systems.
The device in question will protect the machine or installation from an erroneous start. Units block the power supply if a block failure or overheating is planned. In addition, the electromagnetic starter protects against abnormal overloads that can damage the entire system.
Varieties
By types, electromagnetic starters differ in such parameters:
- The usual versions that supply power to the starter, followed by pulling the core with the contacts. As a result, normally closed elements are switched off, and normal ones when power is applied 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. When the power is deactivated, the process is played back in reverse order.
- Reversible modifications. These units are reverses with electromagnets, which have a similar basis and connections for blockers. This design makes it possible to avoid the simultaneous activation of two devices.
By type of connection, the PML electromagnetic starter is divided into categories: AC-1, AC-3 and AC-4. Between themselves they differ in the consumed voltage and type of connection.
For example, AC-1 is an inductive or inactive load, AC-3 is a direct start with a squirrel-cage rotor, AC-4 is a similar system with the possibility of braking and shutdown using reverse current supply.
Features
Electromagnetic starters 220 V, depending on the 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 on condition that they are 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 for light dusting.
- Devices with IP-54 protection do not allow moisture and dust to pass through, can be used outdoors, and not just indoors.
Versatility
The electromagnetic starter is connected by means of signal contacts providing a moment of “sticking”. For example, after a short press of the “Start” key, the ends of the starter are shorted. When holding this button for a short time, the contacts disconnect and remain in a neutral position until they are switched on again after restoring the power supply.
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 analogs with software adjustment, the possibility of an increase or decrease in load, as well as circuits with remote access. There is also a predisposition to introduce the number of contactors with additional blocks or runners with hooks.
Electromagnetic starter "PME"
The thermal relay of the devices in question serves to protect against possible prolonged overload or violation of the integrity of the insulation layer. A special plate is provided in the working circuit, which opens the circuit at critical current parameters. The level of “conflict” is regulated within 15%. From this it follows that overload should be taken into account initially when developing a design project.
The following is not recommended:
- Install in the upper part of the mounting box assembly (hot air mixture will accumulate there).
- Use devices in compartments with a large temperature difference.
- Operate the device on a chassis subject to strong vibrations and mechanical stress.
- Use equipment with a current strength above 150 A.
- Install an electromagnetic starter (380 V) in places where the temperature exceeds 40 degrees Celsius.
Nuances
There are some nuances in the operation of the considered devices. They are associated with the features of the use of starters. The operation is performed by applying a counterflow with an intensive increase in the load on the main contacts. As a result, it is advisable to initially lay a margin of the order of 1.5-2 times in the parameters.
In this segment, it does not hurt to mention analogues with a permanent magnet. They are focused on long-term operation without interruption, are connected through a rectifier device.
Maintenance and care
Maintenance of the PM-12 electromagnetic starter, as well as its analogs, is practically not required until the device has completely exhausted its working life. This is due to the fact that the functional range directly depends on the open / close cycles. They can be several hundred thousand times, if this applies to standard devices used in dry and ventilated rooms.
In the process, it is necessary to monitor the state of the fixing elements. They must be constantly tightened, do not allow moisture and dust, made of appropriate materials. Contact cleansing is very rare, without unnecessary necessity it is better to exclude this procedure from service altogether. This manipulation is indicated in the case of strong melting, burning. Processing of parts is carried out by means of a file with a fine-grained surface.
Exploitation
After prolonged use, the devices in question can make elevated and uncharacteristic sounds. If this moment transforms into regular rattling, you should disassemble the unit, find and correct the cause of the problem. In addition, it will not be superfluous to check the coil and core. Before assembly, it is recommended to treat the work items with a clean rag, and also check the assembly for deformations and cracks.
Technical specifications
The wear resistance of a non-reversible 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 relates to electrical durability, which is opposed to a working arc.
The switching capabilities of the device determine the possibility of turning on the maximum current parameter, which allows not to violate the technical characteristics for wear resistance specified in the instruction. For example, triggering per minute from 8 to 10 times indicates a malfunction of the system.
Synchronization of fuse deactivation indicates smooth operation of the contacts and electrical wear resistance. If a 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 basic characteristics of the electromagnetic starter.
Power consumption can be redistributed to switch and operate the main relay. Features of thermal protection allow you to maintain the integrity of the motor windings, preventing the failure of equipment.
Recommendations
In case of improper operation of the device in question, the difference in damage due to improper start-up can reach 30-40 percent (if incorrect activation of the equipment takes place). Especially at this moment, vibration and bouncing of parts are affected during the switching off of damped indicators at a certain amplitude. The higher the weight of the movable element, the lower the pressing force.
As a rule, the arc formed when the power plant is turned off goes out. The transition moment is usually fixed at zero. At a frequency of 50 Hz, a similar 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. The optimal characteristics are silver contacts.
To summarize
Above were considered the characteristics and features of electromagnetic starters. As can be seen from the review, the devices can operate with voltages 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. Modifications are presented on the market that satisfy user requests for the activation of a separate power unit or the automation of an entire production workshop.