DIN standards definition guide for automotive electrical components. Standardisation of products available from Overview. This part of the standard series DIN specifies codes of terminal markings. Furthermore, reference is made to their basic or index designations. Electric motors. Return line 1). Main connection 1). Self-parking switch-off. Shunt field for reduced-rpm operation, speed 2 for reduced-rpm operation, speed 3.
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Last week, we talked about the relay, and we did our best to keep it simple.
The relay is a remote-controlled switch that works on the principle that a tiny amount staandard current can be used to energize a little internal electromagnet. That electromagnet a little coil of wire wrapped around an iron core then pulls two internal switch contacts together that allow a much larger amount of current to flow.
Terminal markings for motor vehicles – Part 4: Summary
The relay is best thought of as two separate circuits: A low-current control circuit that supplies power standxrd the electromagnet, and a high-current load circuit that is enabled when the switch contacts are pulled together and allows a lot of current to flow to a load device.
Last week we offered a simple example using a relay that turns on an electric motor. It is reproduced below—this time with numbers on it.
What are those numbers? Sometime around the middle of the last century, German cars began following DINwhich is a numbering standard for automotive electrical terminals.
DIN covers far more than just relays. Every DIN relay works this way.
DIN – Wikipedia
It energizes the electromagnet, which connects 30 to 87 and powers the device. It simply connects 30 power to 87 the device. This is overwhelmingly the most common kind of relay found in a car.
In it, the switch inside the relay has not just one position, but two—current can flow to stamdard of two terminals at a time. When the relay is energized, 87 and 87a change places—87 is disconnected from 30, and 87a is connected to Below are two of the relays in my BMW 3. On stwndard relay on the right, you can see the little schematic drawn on the side of it, 72525 looks remarkably like my hand-drawn diagram showing the coil of the electromagnet with terminals 86 and 85, and the switch with terminals 30 and All DIN relays should have the terminal numbers on the bottom.
On mine, you can see the labels for terminal 87 at the top and 30 on the left.
Surprisingly, although the numbering of DIN relays is standardized, the terminal locations on DIN relays are not completely standardized. Terminals 87, 85, and, on a changeover relay, 87a, are I believe always in the same place, but terminals 30 and 86 can switch places with each other.
For this reason, you need to be very careful rummaging through the spare parts box to find a relay if one of yours has died, or accepting one from a well-meaning passer-by.
You can swap them the other way, however—a relay with a resistor or a quenching diode can generally take the place of one without them. Those few twists notwithstanding, to say it again, if you understand that powering terminal 86 and grounding terminal 85 energizes the coil, which then pulls the switch contacts together, connecting 30 power to 87 the deviceyou know what you need to know.
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