Before you start making shunt well, you need to measure the internal resistance of a dial indicator.For this, use an ordinary tester or multimeter (either dial or digital).At the same time, it is necessary that the current through the device under test is not too large, otherwise it may be deformed hand.
now calculate the voltage required to apply for an indicator to his hand strayed completely.To do this, set the full deflection current in amps, and the measured resistance of the device - in ohms.Then substitute them in the standard formula of Ohm's law: U = IR, where U - voltage necessary for the complete rejection of the arrow, I - current full deflection, R - measured resistance frame indikatora.Ne surprised
that calculated by this formula, the voltage will verysmall.
Now we need to calculate the resistance of the shunt well.It would be so small as compared with the resistance indicator frames that the latter can be neglected.Resistance shunt and must be such that during the passage of current through it, which is to limit ammeter on the shunt E of the incident voltage equal to the calculated under the previous formula.Thus, this resistance can also be calculated by the standard formula Ohm's law, but converted as follows: R = U / I, where R - desired resistance shunt and, U - naprzhenie full deflection of the indicator calculated by the above formula, I -the current limit, the measurement of which will be calculated your ammeter (if it is expressed in milliamperes, set it to the pre-amps).
Properly connect between an indicator and a shunt .Namely he shunt inserted directly in open circuit, in which the current to be measured, and connect the wires to light it.Esi do the opposite, including indicators in open circuit and a shunt connecting wires to the indicator, the latter tipped the scales, or even burn.Think about why.
Make a micro ammeter new scale having graduation in milliamperes or amperes and an appropriate scale.
Connecting and disconnecting Perform when de-energized circuit.Observe the polarity.When measuring AC use indicator in conjunction with the detection circuit.