OSM transformers are step-down transformers of armored, rod or toroidal type, designed to power lighting, control and automation circuits. They are designed for power from 0.063 to 4 kVA. Depending on it, transformers differ in dimensions, mounting method and special impregnation with moisture-resistant insulating varnish. The primary winding is designed to operate under voltage from 220 to 660 V. The secondary can operate from 12 to 260 V. It is possible to have several secondary windings for different voltages. Thus, the scope of transformers is quite wide.
What are OSMs?
What are OSM transformers can be understood from the name itself. In this case, O is single-phase. C - means dry, not using transformer oil. This is due to low power and has a positive effect on weight and size. A special varnish is used to protect against moisture and oxidation. The M means it's multipurpose.
The type of protection against electric shock is class I, and the degree of protection is IP00,however, the customer can make the transformer with IP20 contact protection. It should be taken into account that transformers are not designed for installation in an explosive environment.
Withstand vibration load with a frequency of 10 to 60 Hertz. The maximum acceleration in this case should not exceed 2g. Able to withstand impact up to 8g acceleration.
Note that in addition to the design of the armored type, there are also OSM T transformers. In this case, T means that it is of the toroidal type. Roughly speaking, it has the shape of a donut. With the same power, such transformers are lighter and smaller in size.
Design
Transformer OCM 0.25, 1 or 4 kVA can be armored, rod or toroidal type. The choice of one or another option depends on the manufacturer, its capabilities and equipment. The type used has no significant effect on performance or reliability.
Cores for all options are made of electrical steel. In rod and toroidal type transformers, the winding contains a core. But in armor, on the contrary, the core contains a winding.
The coils have a frame construction. The material used is copper. The wire is encased in heat-resistant insulation.
The beginning of the secondary and primary windings is indicated on the top of the transformer. The first corresponds to the designation "O", and the second - "U".
Installation Features
The transformer is intended for installation in equipment in which all protection measures: against electric shock, water ingress and overload - are carried out by the equipment itself. The windings are impregnated with moisture insulating varnish, carried out in a vacuum chamber. It is not recommended to install transformers in environments where there are fumes containing alkalis and acids that can damage the materials from which the components of the device are made.
Each shoe clamp is designed to accept no more than two aluminum or copper wires. Their maximum cross section should not exceed 2.5 mm. The case of the device must be grounded. The output of the secondary winding is also grounded if it is used for lighting. For safe operation, the insulation resistance must not be less than 0.5 MΩ.
Transformers from 1.6 kVA are designed for installation on a horizontal surface only. Models with a power of 1 kVA and below can be installed on both horizontal and vertical surfaces.
Types of climatic design
OSM transformers can be made in the following versions:
- U3 - the first letter in this case means a temperate climate in which the transformer can operate. 3 is the accommodation category, namely indoors with natural ventilation.
- T3 - designed to work in tropical climates, both with dry air and with high humidity. The accommodation category is the same as in the previous option.
- UHL3 -stands for temperate or cold climate.
Thus, all options are for indoor use only. Outdoor work or under a canopy is not provided. They differ from each other only in a protective coating from the external environment, but the characteristics of OSM transformers and dimensions are the same.
Deciphering indices
You can often see different indices for OSM transformers: 0.4, U3, 380 and so on. Let us analyze in more detail what they mean, using the example of OCM1-0, 5-U3-380 / 5-36-220 / 12 TU:
- The number 1 at the very beginning indicates that the transformer is the first model.
- 0.5 - rated power. Please note that if the transformer is three-winding, the power will be indicated as a total for two windings.
- U3 is the climatic conditions of work.
- 380 for this case shows the voltage on the primary winding.
- 5-36-220 are the voltages on the branches of the secondary winding. In this case, there are three.
- 12 - voltage of the third winding.
- TU stands for specifications.
Transportation and storage
During transportation, it is necessary to exclude any possibility of mechanical damage to transformers. Boxes must be securely fixed in the manner provided by the respective freight transport. It is also important for storage and transportation to prevent the possibility of moisture or dew on the surface. Store at a relative humidity of not more than 80 percent. Unacceptablethe presence of acidic or alkaline fumes that can damage the materials of which the transformer is made, its impregnation or insulation, or cause the appearance of oxide.
