High voltage heaters (HVH) are used to control interior vehicle temperature and for the protection and management of different onboard systems, such as batteries. Because HVH’s convert DC current into heat with practically no loss, they are a technology that is often considered by manufacturers. Depending on the vehicle (small cars, buses, trucks, etc.), high voltage heaters are developed for different operating voltages, with heating power up to 10 kW.
The production process of HVH’s involves many steps, with some of them being manual. Various tests are carried out in-line, according to the corresponding manufacturing stages. Depending on the type of heater, voltages of 100 to 900 V DC are applied directly on the heating layer unit. At the same time, this voltage and corresponding current is measured in order to check the function of the control electronics. As there is a risk of electrical shock, no assembly may take place on the workpiece during this testing.
Requirements of Application
To obtain reliable test results, it is important to use accurate and reliable measuring equipment. The use of laboratory equipment in a production environment is not always practical. High quality devices proven in industrial applications are therefore used for end-of-line test stands in addition to within the research and development phases.
The Knick P29000 is a voltage transducer that can safely measure voltages up to 1000 V DC. Accuracy is maintained through a gain error < 0.2 % of the measured value. Safety is ensured by way of 3-channel transformer based electrical isolation at a working voltage of 1000 V AC/DC. Additional electrical safety is proven with the P29000’s test voltage specification of 5.4 kV AC. Flexibility is gained through selectable input and output ranges by way of onboard dipswitches.