Thread: Relay experts please

Check to see if it's a changeover relay, i;e 87 and 87a

Each pin on a relay has a number,
My local auto supplier has Narva relays, they matched a yellow relay for me by checking the value of each pin and the exact order, the pins have various values in different orders.

As for aluminium vs plastic, not sure
the plastic one's are made by siemens, maybe siemens didn't make a relay with the pin values required.
There may be another explanation, as i wondered the same thing myself

Originally Posted by Waxenwane

Check to see if it's a changeover relay, i;e 87 and 87a

What's a change over relay showing my ignorance of all things electrical

Originally Posted by scott oz

What's a change over relay showing my ignorance of all things electrical

Changeover: has contacts either side of moving arm so you can use the relay to change over from one path to another i.e. no power to relay: connection is 30 to 87a, power on: connection is 30 to 87.
All relays regardless on their can colour/shape/material meed to be checked for the exact pin configuration, adequate amp rating and correct voltage.
Correct relays save fuses!

Originally Posted by bee utey

Changeover: has contacts either side of moving arm so you can use the relay to change over from one path to another i.e. no power to relay: connection is 30 to 87a, power on: connection is 30 to 87.
All relays regardless on their can colour/shape/material meed to be checked for the exact pin configuration, adequate amp rating and correct voltage.
Correct relays save fuses!

OH, I chucked in a spare 5 pin relay and it is working without problems. but may be the Amp rating is not to spec?
The Alloy relay is a lot dearer

Originally Posted by It'sNotWorthComplaining!

OH, I chucked in a spare 5 pin relay and it is working without problems. but may be the Amp rating is not to spec?
The Alloy relay is a lot dearer

Read an article recently in Silicon Chip magazine about auto relays. The short story was don't assume the pin out is standard even with relays from the same manafacturer.
In the example discussed an old driving light relay had been replaced with a new one which worked fine, or appeared to do so. Operating the driving light switch turned the driving lights on and off, but electrically the relay had been bypassed and the switch was doing all the work. How this fault showed up was that the battery would go flat after a couple of days of non use. This was because the relay coil was 'on' all the time and doing nothing but draw current. Old Bosch relays used to be metal cased, and in this case have a different pin out, newer ones plastic cased.
Electrically it doesn't really make any difference what the case is made of. The current rating of the relay is usually writen/stamped on the case. ie. 30A = 30 Amps. DC Voltage rating shouldn't be an issue as 12 volts is neither here nor there.

Deano

Originally Posted by It'sNotWorthComplaining!

OH, I chucked in a spare 5 pin relay and it is working without problems. but may be the Amp rating is not to spec?
The Alloy relay is a lot dearer

Most likely the 87a pin of the relay is not connected in the socket. Most of these little relays have a rating of at least 20 amps so should run a pair of 100W spotties or a similar load without trouble.

If at all in doubt check your socket and relay bottom with a magnifying glass, all pin numbers should match the old relay, spare pins are optional so long as the socket has no connector there.

Land Rover fuel pumps dont use headlight type relays AFAIK.