All About Relays
If you have the German Relay Number, starting with either 4RD or 4RA, please click here for a cross reference list. Please Click Here to choose Relays by Type and Voltage. Hella manufactures many relays and not all versions are available individually; some can only be purchased in bulk. In addition, not all relays Hella makes are available to the after-market. | ||||||||||||||||||
What is a relay and why use one?A Relay is a remote-control switch. An electro-magnete operates the contacts through which the main current flows. With the use of a relay, the circuit carrying power to a device can be as short and direct as possible. This reduces the losses through the stock wiring due to their circuitous path. | ||||||||||||||||||
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Eliminating voltage spikes: Relays with a Resistor or a Diode.Voltage spikes from 300V to 500V can occur momentarily when a relay is switched. Sensitive electronic equipment can be damaged or malfunctions can occur if these spikes reach the vehicle electrical network without suppression. A relay with a resistor reduces these voltage spikes to less than 100 Volts. A relay with a diode eliminates them completely. The correct polarity of the connections is marked on the diode protected relay. | ||||||||||||||||||
Dual 87 RelaysThis relay has two High Current output terminals so you don't have to splice the wires from two lamps together before connecting to the relay (Configuration B2 below). Integral FuseSome Relays have a Fuse built into them so you don't have to have a separate fuse holder. | ||||||||||||||||||
The most common pin layouts are shown below | ||||||||||||||||||
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