What is this used for and what is it? (Wooden base, metal strip connecting two terminal blocks with finger nuts and small screws.)

Question

This was handed to us and I have no idea what the device is, or what its usage is.

I've edited your question title to be more meaningful in search engine results. — Transistor, Nov 19 '22 at 09:32
Looks about 1930s, definitely current shunt. As the resistor appears to be soldered into the terminals, the small screws are probably Kelvin connections. — , Nov 20 '22 at 14:05
I tried to edit the question but made a mess. You can find it now again. — Pococurante Bird, Nov 21 '22 at 05:43

score 17 · Answer 1 · answered Nov 18 '22 at 23:29

It is a resistor designed to be used as a current shunt. The "10" indicates it is rated for 10 amperes. The current to be measured is attached to the large screw terminals. The voltage dropped by the shunt is measured via the small screws. Usually, the shunt will drop anywhere from 10 to 100 millivolts when the rated current is applied.

score 15 · Answer 2 · answered Nov 19 '22 at 02:10

15

It appears to be a demonstration device to illustrate "shunts" to students, based on the wood base.

Similar to this commercial device with a bakelite base. Note that it has four connections, two high current, and two low current, and that they are arranged in a specific manner.

answered Nov 19 '22 at 02:10

Spehro Pefhany

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"arranged in a specific manner" - isn't this way worse than having the measuring contacts at the outer edge? The contact should be outside the main current path to not be dependent on slight misalignments of the exact point of contact. – asdfex Nov 19 '22 at 11:09
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@asdfex I think this is the right way to do it. The sense terminals are as close as possible to the (relatively) high resistance element and well inside the high current terminals so the current near the sense terminals is independent of the nature of the high current connections. – Spehro Pefhany Nov 19 '22 at 17:01

score 2 · Answer 3 · answered Nov 19 '22 at 00:55

Sure it is a current shunt.This means that you can use your multimeters on the volts setting to measure current .This approach is more idiot proof because if a multimeter on the amps setting is mistakenly used across a voltage source it could be ruined by high short circuit currents . So your device should be kept.

What is this used for and what is it? (Wooden base, metal strip connecting two terminal blocks with finger nuts and small screws.)

3 Answers3