Tech Power Electronics offers a very broad range of skills in power electronics and industrial electronics, ranging from the components themselves to electronic board assemblies and integration of components into complex assembles.
Passive coiled components and electronic cards
Tech Power Electronics’ main fields of activity are railways, energy conversion, industrial equipment, safety lighting and the medical and nuclear industries. Products range from passive coiled components (inductance, transformers, etc.) to electronic cards (CMS and traditional), all of which can be mounted into complete equipment.
Our development team includes engineers and technicians capable of studying the specific requirements of market operators and developing and testing products for customers’ specific needs.
Line transformers for wired telecommunications
A line transformer is specially designed for wired telecommunications. It creates a galvanic separation between two circuits carrying digital or analogue data without disrupting the circuits’ symmetry. In certain cases the line transformer can adjust impedance. It only transmits differential mode signals with a frequency matching its bandwidth.
Galvanic separation eliminates common-mode disturbance generated by:
- Connections with power lines
- Industrial interferences
- Atmospheric discharges’ currents
The line transformer’s bandwidths and magnetic saturation eliminate differential mode disturbance generated by accidental contact of the transmission line with the power line, and interfering signals outside the bandwidth (radio transmitter).
There are four main types of transformer, listed below.
Derivation line transformers
Derivation line transformers allow a parallel connection to the cable. They have high impedance in order to not disturb the cable’s impedance.
Interrupted-line line transformers
Interrupted-line line transformers connect different sections of cable. The impedance is identical on both sides, and the conversion factor is 1:1. The closer the transformers are to each other, the weaker the common-mode voltage interferences on each section will be.
Terminating or end-point line transformers
Terminating or end-point line transformers adjust the impedance to the terminating equipment and protect it, to prevent de-coupling of the phantom circuit.
50Hz single-frequency line transformers
50Hz single-frequency line transformers are used on alarm circuits at derivation points and in amplification units.
Blocks of line transformers
Blocks of line transformers include two or four transformers with identical functions.
HDSL line transformers
HDSL line transformers are used to transmit data in frequency bands from 50kHz to 2MHz.
SHDSL line transformers
SHDSL line transformers are used to transmit data in frequency bands from 7kHz to 200kHz.
‘Pupin’ load unit
In a telephone line that is not inductively loaded, attenuation increases according to the frequency’s square root. The resistance attenuation of a telephone line can be reduced if the linear capacity effect is neutralized by increasing the self-inductance of the line.
This self-inductance effect is obtained by inserting loading coils at regular intervals, the inductance of which is defined according to the cable’s self impedance and capacity characteristics.
In a ‘pupinised’ line for a given distance between coils, attenuation is virtually constant for a frequency bandwidth wider when the inductive load is lower. Load units are set in a weatherproof metal box.
There are three main families:
- Regional and long-distance units with two and three coils
- Urban units with four coils
- Urban units with two coils
Building-out line section
A building-out line section used with a pupinized cable is a set comprising a capacitor and resistors grouped so as to represent the capacity and resistance of a section on cable shorter than one coil spacing. The dimensions are 55mm x 40mm x 64mm.
50Hz filtering block
Telephone circuits located near and running parallel to electrified railway lines are subject to induced longitudinal electromotive forces. The 50Hz filtering block protects them against overvoltage from 25kVAC lines and 1,500VDC or 3,000VDC lines used as power sources for railway traction.
It can be used for two functions:
- At the end point: inserted between the line terminal and the pothead, it filters induced voltages and injects the remote power feed current
- In-line: to limit induced voltages and currents, interruption points are required in-line
The filtering block is fitted at such interruption points. The continuity of the DC phantom is ensured by the high internal impedance, which filters out the 50Hz wave and its harmonics.