Booyco Engineering has an established reference base of climate control systems within the railway sector which include both heating and cooling systems. One such system, custom-designed and manufactured for a specific rolling stock or locomotive requirement, is the PTC heater. This footwell cab heater was developed for the Class 40 locomotive which was, at that stage, being refurbished.
Ayanda Boltina, project engineer at Booyco Engineering, says that the selected locomotive has a generous supply of 74VDC power and a limited 24VDC power supply available from the auxiliary generator and voltage converter respectively from which the heater can draw power.
“The traditional heating method in locomotives incorporates the use of a fan and typically 5mm diameter rod heater elements, made from resistive (Incoloy) alloy, which are coiled and placed into the air path. Due to the high air bypass rate in this application, the application-dependent heater efficiency of this method is between 70% and 80%. We researched alternative heating technologies for the application and positive temperature coefficient (PTC) heater elements were selected.”
A 24 VDC brushless electrically commutated (EC) centrifugal fan was used for the heater, which resulted in the heater unit’s in-rush current being virtually the same as the running current.
The large finned heat exchange surface area of the PTC heater results in high heating efficiency (96%-98%), effectively saving electricity consumption and increasing product life. In addition, the PTC heater offers very low air resistance and a long service life, with no electrical noise and a fast thermal response time with low inrush current. The heater bank does not burn or ignite when in contact with paper, matches or clothes, further enhancing the safety of the heater.
“The PTC heating component is installed with an internal safety protection device, so that when it is used abnormally current will automatically be reduced to maintain safety. This means that there is now no need for a cycling thermostat,” Boltina explains.
“The PTC heater elements are installed with a double-insulation heating device, which is suitable for installation in high humidity, without causing electricity leakage when it comes into contact with metal.”
Prior to actual installation, these heater units were manufactured, assembled, tested (capacity and vibration / shock) and commissioned on a locomotive. “We need to engage in this type of product development and technology design in order to make tangible gains in the marketplace and thereby ensure customer growth,” Boltina concludes.