| 摘要 |
The invention concerns an improvement and development of test apparatus for the electrical tap at a vehicle, designed to illuminate the trailer. The test apparatus consists of a box, provided with indicator lights, which is connected by cables to a multipole contact which is designed to connect to the electrical tap of the vehicle. The test apparatus is characterized in that it is provided with an indicator arrangement for automatic checking of faulty ground connection. The test apparatus A is connected to the vehicle's tap U. If, for example, the pin a in this tap is placed under tension, current flows through the light diode D1a and the resistor Ra and on to the pin g of the tap, which is grounded in the vehicle. If this ground connection is absent, the following occurs. The current instead passes through the light diode for ground fault indication D2 and one or more of the diodes D3 which prevent the pins a- f from making a connection. Finally, ground is obtained by the vehicle's lights Lb-Le, which are not turned on. Even if a normal ground connection is absent, one therefore has a distinct indication of which pin in the tap is placed under tension, and at the same time one is informed that a grounding fault exists. <IMAGE> |
