Composition of a low-voltage transformer
A transformer consists of two parts:
- The primary winding
- The secondary winding
The primary winding
This is the part that receives power from the transformer.
The primary consists of one or more coils with a number of turns. Depending on the number of turns, a magnetic field is generated from the input voltage.
The secondary
This is the part to which the load is connected.
The secondary part also consists of one or more coils with a number of turns. Depending on this number of turns, a magnetic field captured by the turns will generate a proportional voltage.
The transformation ratio (ratio between the primary and secondary voltage) is directly related to the ratio of the number of upstream and downstream turns.
Both parts, primary and secondary, will have a magnetic circuit that will pass through the primary and secondary windings. This is in order to better direct the magnetic field and thus maximise the efficiency of the transformer.
How to choose your transformer
In order to choose your low-voltage transformer, you will need to determine the following:
- Elements related to the primary: voltage value, type of network (230 volts single-phase, etc.)
- Factors related to the secondary: voltage value, device consumption (which will determine its power), type of network required, voltage drop, and power factor
There are different types of transformers:
- Isolation transformers
- Safety transformers with a voltage lower than 50V
- Isolation transformers
- Medical transformers
- Autotransformers
It is generally considered that two powered products cannot start up simultaneously (start-up current peak). At most, 70% of devices are in operation at the same time. Please note that the location of the installation must of course be taken into account.
What about the autotransformer?
The autotransformer is a coil with outputs at different points on the coil, allowing the voltage to be reduced. Compared to a conventional transformer, it is more compact and has better efficiency, but has the disadvantage of not being isolated from the main circuit (higher short-circuit current).
In summary, to choose the right transformer, you must first:
- Determine the consumption elements
- Determine their supply voltage
- Determine the installation method (on a rail or on a plate) based on the power
- Choose the range based on the desired use and safety requirements
