Upgrade of air conditioning and heating of RegioJet passenger cars

ABOUT THE PROJECT: Customer: RegioJet, a.s., Year of implementation: 2013-2016, Number of vehicles: 40, Place of operation: Czech Republic

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The aim of the project is to replace a substantial part of the electrical equipment of passenger cars, which showed a high failure rate and considerable maintenance requirements due to its wear. After having analyzed the problems and based on experience from vehicle operation, the customer was looking for a solution not only to replace an obsolete air conditioning unit powered by a high voltage motor with a high frequency of failures, replace the air conditioning and heating control circuits, but also to replace a non-compact original high voltage converter called CZE (central power supply).

Based on an analysis of the customer requirements and a more detailed survey of the condition and design of the original electrical equipment, a decision has been made to completely replace the air conditioning unit, air conditioning and heating control circuits, as well as the high voltage converter (CZE). The container of the electrical heating, evaporator and vehicle air supply fan remain original, but with an upgrade and addition of new analog temperature sensors based on NTC sensors.

The customer's wish was also to consider the omission of unreliable and obsolete components of the system of detection of connected traction power supply system and configuration power high-voltage circuits. Based on these requirements, we designed the integration of a compact central power supply converter designed for installation under the vehicle, which allows operation on all standard power supply systems of the traction system. In order to be able to cancel the detection and configuration high-voltage circuits, the wiring of the original high-voltage heating bodies had to be changed to a new power supply from a three-phase network (3x400V / 50Hz), which is powered by the new integrated converter.

Based on an analysis, labor requirements and the low required price for renovation, our company developed its own new controller unit, which is designed as a two-board unit (interface board and processor unit). Both units (boards) are connected to each other and connected by means of comb connectors. The set of control boards is stored and mounted in a holder made of aluminum profile, which can then be installed on a standard DIN rail. The entire control unit, including the bracket, is installed on the side wall of the air-conditioning unit's control cabinet. The location of the new control part (circuits), including the new power contact switching elements, was proposed and subsequently designed as a switchboard cabinet – inserted in the side of the new air conditioning unit – access from the side of the vehicle for easy access by maintenance technicians. In addition to the contact elements (contactors) - which control the power supply to the air conditioning compressor - and a total of four levels of electric heating, this cabinet also contains all the necessary protection elements (circuit breakers and residual-current devices) to protect the heating and air conditioning compressor circuits.

The project also required a design of the method of electrical connection of the innovated part (in particular control circuits) to other unchanged electrical equipment of the vehicle. This includes, but is not limited to the connection of logic or analog signals such as: presence of vehicle power supply, undervoltage protection of batteries, supervision of air flow and correct operation of the supply fan, connection of protective thermostats of heating ducts / evaporator, action elements such as supply air fan motor supply contactors, air conditioning cooling circuit solenoid valve control, control of the original status indicators located in the vehicle switchboard, control of the heating of the boarding areas, control of the original recirculation dampers, etc.

An integral part of the project was also the solution of the issue of measuring and control of temperatures in individual compartments of the car. Each compartment contains an electromagnetic damper, which can be controlled in two states in the open - closed mode. After analyzing the original parts of the compartments - which were to be preserved for financial reasons (air ducts with electromagnetic dampers) – we decided to develop and replace the original units with switches for the adjustment of the required temperature, measurement of the room temperature and control of the electromagnetic damper – to develop a new processor unit which included the development of application software, which enabled easy installation and the provision of the necessary local functionality. The compartment units were designed with the implementation of a full-duplex RS485 communication line. The RS485 line is installed across the entire vehicle and all individual modules. Each module connected to the communication line has a preset unique address. The module is thus unified in terms of hardware and software. The RS485 line is also brought to the central control unit, which has, thanks to the compartment modules, accurate information on the temperature in each compartment, is informed about the preset temperature by the passengers, and is able, on the basis of the actual and required temperature, to influence the switching on or off of the relevant control damper in each compartment and thus achieve the optimal temperature according to the passengers’ requirements.



  • Compatible with TST (Tuning and Service Tool)
  • Advanced diagnostics, event logger and operational data recorder
  • New temperature control in each train compartment
  • High reliability of electrical components
  • Renovation of some of the original components
  • New control circuits
  • Preparation of complete documentation for the air conditioning system

Technical parameters

Rated cooling capacity

50 kW

Rated heating capacity

33.5 kW

Rated power supply voltage

3 x 400 V, 50Hz

Rated control voltage

24V DC

Refrigerant in the compressor circuit



680 kg

Maximum air supply

11,800 m3 per hour

Operating temperature range

-40°C to +45°C


POLL, s.r.o.

Výpadová 1676/4a
Praha 16
153 00

IČO: 62967754