# Student Needs Help!!! What is a shunt in an EV?



## jeremyjs (Sep 22, 2010)

go to wikipedia, type in electrical shunt, read the part titled "use in current measuring"


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## dougingraham (Jul 26, 2011)

mcmichaelev said:


> I'm a student trying to learn about Electric Vehicles. I need to know what an Shunt is, in plain English so I can understand!!!!! ((Not a Shunt Motor))


A shunt is a very low value calibrated resistor. Its purpose is to measure the current that is passing through it. And they are generally specified by a current and millivolt rating. A 1000A 50mv shunt would have a resistance of 0.00005 ohms (0.05v/1000a). If you run 1000 amps through it the voltage across the sensing terminals would be 0.050 volts. In the case of this example if you read the voltage across the terminals you divide by 0.00005 to get the current.


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## Conelrad (May 23, 2009)

There is lots of factual info already, so I'll add a simplification:

Shunts are used in DC circuits. They usually look like a big chunk of brass or copper, mounted on some sort of insulating base, installed in a heavy gauge wire path.

They allow you to 'sample' the current flowing through it for metering purposes.

For instance, you may have up to a thousand Amperes flowing, and that would be very impractical to route through a dashboard ammeter or other measuring circuit.

A shunt takes a bit of that flow in a precise ratio and is much easier to handle for measurement.

DG


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## mcmichaelev (Dec 3, 2008)

thanks for the help in clearing it up!


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