LCON threshold switch for modern sanding systems

NOWE GmbH, a company of the "Faiveley Transport Group", delivers innovative and reliable sand scattering systems that are modular in construction and specially designed to customer requirements. LÜTZE components ensure a precise metering of sand quantities and guarantee safe operation even at low temperatures.

Humidity, dirt or leaves on the track reduce the level of traction in the wheel-track contact.  This can significantly increase the acceleration and braking distance. Besides inhibiting the operational safety and wasting energy, it also causes excessive wear of the wheels or tracks.  To create the required amount of friction, sand is applied into the wheel-track gap by compressed air.

As part of a new tram project, LÜTZE components are being used for the temperature control and compressed air supply in the sanding system. Two LÜTZE temperature signal converters with PT100 input record both the ambient temperature and the heat pad temperature. The analogue signals are processed by a PLC which can also actuate the heating of the drain valve and heat pad when required via a LÜTZE semiconductor module. A LCON threshold switch automatically controls the temperature of the valve block. The temperature is monitored by a PT100 installed in the valve block which is then transmitted to the LCON threshold switch. If the temperature drops below 10 °C, the heating is activated by a LÜTZE semiconductor module. The PT100 sensor is also monitored for wire breaks.

By using these compact modules with an installation width of just 6.2 mm each, the complete temperature control circuit can be housed in a small switch box inside the compressor box.

Modern sanding systems only release the amount of sand that is actually required. This reduces the operating costs as well as the amount of dust pollution for the environment.

Solenoid metering devices are used to meter the exact quantity of sand. They are actuated with a pulse frequency between 1 and 10 Hz. The company NOWE also relies on LÜTZE components to actuate these metering devices.  Due to the high switching frequency and inductive load, the decision was taken to use semiconductor modules. Regardless of whether the vehicle has a 24 V or 110 V supply – LÜTZE offers the right solution for every application.

Andreas Schindler, LÜTZE Germany