Technical characteristics of the PML starter: description, principle of operation of the magnetic device, care

Many modern manufacturers are engaged in the manufacture of contactors, as well as magnetic starters. All models are combined in a series for specific characteristics. PML products common among electricians are presented in the form of small-sized switching devices. They are supplied to those circuits that are located in the current range from 9 to 95 A. But such actions are possible only after studying the technical characteristics of the PML starter.

Brief description of the device

A universal electromagnetic starter is considered an indispensable unit that perfectly combines different types of switching mechanisms, necessary not only for reverse and start, but also for stopping motor. Pushbutton stations, relays, contactors and switches also fall into this category.

Specific control over the operation of the engine is simply impossible without a non-reversing and reversing starter. In addition, it is these two functions that ensure the timely start and stop of the vehicle's motor. The PML starter has found wide application in pumping and ventilation systems, escalators and elevators, as well as many other installations where there is a need to configure the remote control of devices with working mechanisms.

The design of such a device is no different from similar devices. The robust plastic housing houses a powerful core and anchor. There is also a universal pulling reel. The final scheme of the PML starter differs in such a form of filling that traverse-type guides are mounted in the upper compartment, and an anchor is already located above them. Near this unit, experts have provided for the presence of hardy bridges with small springs intended for blocking contacts.

The principle of operation of the PML magnetic starter differs in that at the moment the electric current is applied, voltage begins to collect in the coil. During this, the magnetic armature is attracted, which gradually closes the open contact and opens the closed one. Then the used magnetic starter is disconnected. Control over this situation is quite high, since the springs fix all the moving parts of the system. After turning on the magnetic starter, everything returns to its place.

Experienced craftsmen often use the so-called RTL and PKL attachments, which are installed depending on the size of the main PML unit. This approach allows you to increase all operational parameters. Set-top boxes from the PKL series differ from their counterparts with the following characteristics:

• The unit operates at temperatures up to + 500˚С.
• The current power is 16 A.
• PKL prefixes can be used by craftsmen as additional accessories, where the frequency is 50 Hz.
• There is protection from IP 00 to IP 40.
• The type of current used belongs to the category AC, DC.
• Long service life - over 3 million cycles.

It should be noted that a maximum of one attachment can be installed per starter.

Functionality

PML contactors are presented in the form of powerful cases, which are molded from durable plastic, the product itself is divided by the manufacturer into a base and a head part. The rod core also has two compartments. Each of them is located in a separate part. Hardy contacts are mounted in the head compartment, which most of all resemble the bridges of a moving system. They are necessarily spring-loaded and rigidly attached to the core using a traverse. Of course, the final dimensions of PML switches are relatively small, which is why they belong to the category of small-sized units.

In the head part there are guides along which the movable system moves freely. All those terminals that are used to fix the output and input circuits are installed in the same compartment. A coil spring return provides a normal open condition for the contactor. It is mounted between the body parts. It is only thanks to the efforts of this spring that the movable system is fixed in the upper position with open contacts.

Timely magnetization of the W-shaped core occurs due to the influence of the control voltage of the required value, which is supplied to the critical terminals of the main coil. During such a reaction, there is a convergence and closing between different parts of the magnetic circuit. As a result, the power contacts are closed, and their free analogs change their voltage.

Since the control AC voltage with an industrial frequency of 50 Hz can cause a specific rattling effect of the moving section, the manufacturer has provided for the presence of closed rings. They are mounted on both sides of the central core of the magnetic circuit, reliable fixation is due to factory pressing into special grooves. All currents that act on these rings are able to slow down the change in magnetic flux in the core, minimizing rattling rates.

Installation and setup

To ensure long-term and well-coordinated operation of PML magnetic starters, the installation of such units should be carried out exclusively on a flat surface. The unit is rigidly fixed in an upright position. If the master decided to install starters with a specific thermal relay, then he must definitely monitor the minimum deviations in the ambient temperature.

Poor installation or any other errors can lead to negative consequences and false alarms of the unit. For this reason, it is worth avoiding those areas that are most susceptible to vibrations, mechanical shocks and strong shocks. For example, quite strong shocks and vibrations during start-up are created by a powerful electromagnetic device PML with rated current values ​​of 150 A.

Modern heating units can be subjected to additional heating from other energy sources. Such operational features negatively affect the operation of the units themselves, because of which they can often break down. Masters do not recommend installing the relay next to other equipment that generates heat during operation.

If only one conductor is connected to the contact terminal of the starter, then its end must be bent into a ring or give it a U-shape. This locking method helps to prevent the spring washers, which are located in the clamp, from skewing. When two conductors with identical cross-sections are connected to the terminal at once, it must be remembered that the ends of the wires must be perfectly flat. Only then can they be positioned on both sides of the clamping screw.

Before connecting copper wiring, all ends must be tinned. If the master decides to use stranded products, then they should be carefully twisted before tinning.

The aluminum ends of the wiring are cleaned with an exceptionally small file, after which the bare areas are covered with technical vaseline or paste. Any lubrication of the moving parts and contacts of the unit is considered simply unacceptable, as this is fraught with a short circuit.

Before putting the PML magnetic starter into operation, it must be carefully inspected in order to exclude the presence of defects, chips and any other damage. All moving parts must be free to move by hand. At the final stage, all electrical components are checked against the diagram.

Advantages and disadvantages

The practical design of the magnetic starter includes several basic elements - a robust housing, made of dielectric material, springs, coil and contact block with moving part core. It is these parts that are responsible for the performance of the entire unit. The core and coil form a specific electromagnet. But, despite the fact that such a device has a simple type of design, it has both positive and negative sides. Among the advantages are:

• The presence of a remote control method, due to which the master can control the operation of the starter from any place.
• General availability.
• Reliable overload protection.
• Simple working principle.

The positive sides of the PML starter are enough for the main unit to work properly for a long time. But do not forget about the disadvantages:

• The device cannot be restored, as this process is considered extremely complex and time consuming.
• Only a qualified specialist can connect the starter, who will not allow a short circuit.
• Even waterproof models are unable to cope with water ingress into the case.

Methods for fixing the PML starter

Its performance depends on how accurately and reliably the unit is installed. Specialists know several options that they actively use in their work. But for the household industry, they are most suitable the two most effective ways:

1. With bolts.
2. DIN rail mounted.

Fastening with heavy-duty bolts

There are special holes in the lower section of the circuits, which are intended solely for the installation of the unit. The number and diameter of the bolts depends on the modification of the equipment used. In order to securely fix the case, in the panel itself it is necessary to apply markings and drill auxiliary holes with a drill, where the thread will be made.

It should be noted that this method has undeniable advantages - high strength and minimal financial costs.

Installing equipment on a DIN rail

Many experienced craftsmen most often resort to this particular option, where a plastic or metal strip with curved edges (36 mm wide) is used for work. In those devices that were originally created for fixing with a DIN rail, manufacturers have provided slots with movable elements. During installation, this part moves away, and the device itself is put on the rail and secured by returning the moving part to its original position.

This method has some advantages:

• All failed elements can be quickly replaced. Careful dismantling of faulty and installation of new parts takes place without unscrewing the bolts.
• Sufficient ease of installation. During installation, the master does not need to drill new holes for each element separately, since only one small strip needs to be fixed. In plastic boxes from renowned manufacturers, the DIN rail is presented as a single piece with a housing.

Care rules

In order to maintain a magnetic starter in appropriate conditions, it is necessary to know well all those malfunctions that such a unit most often encounters. This includes a sharp rise in the temperature of parts and a strong hum of the equipment.

Overheating is mainly associated with turn-to-turn closures of the coil, and in this case, you cannot do without replacing it. Heating of parts can occur due to an increase in the voltage in the mains.

Strong humming of the unit is observed in many cases. Among the main reasons - poor fit of the armature to the core due to contamination or damage to their surface. Other factors include jamming of the moving part and a decrease in the nominal voltage in the network (by 15% or more).

You can only avoid negative consequences with the help of timely care. The huge advantage is that such a unit does not need expensive maintenance. The master only needs to prevent dirt, dust and moisture from getting into the device. The tightness of the terminals and the condition of the contacts must be checked regularly. In addition, you can resort to a certain list of measures that are often used by electrical specialists.