The ampermeter of a direct current consists of the magnetoelectric indicator and the shunt - the powerful resistor of small resistance. The lack of the rectifier does characteristic of such ampermeter close to linear.
Instruction
1. Use shunts only from a set of delivery of the ampermeter. Any other will lead to considerable distortion of indications. It is connected with the fact that magnetoelectric indicators of different brands even with identical current of a full deviation of an arrow have various internal resistance.
2. Choose the shunt calculated on limit current is slightly lower than measured. For example, if it is supposed that current in a chain can change ranging from 5 up to 8 A, use the shunt on 10 A.
3. On screws of the indicator there are about two nuts. Turn off from each of screws only the first of them. The second, located closer to the case, do not turn off, otherwise the screw will fail inside, and for repair of the device it should be opened. Then, if before it was exposed to check, it will be required to carry out this procedure anew.
4. Put on the shunt screws and fix them by nuts. Do not forget about two washers which have to be located between the shunt and the second nuts of each of screws.
5. Cut off power the device which consumed current you want to measure. Break off a chain of its food then, observing polarity, turn on in a rupture of a chain the ampermeter with the shunt. Clamp wires between washers. Include food, read indications then again cut off power a chain, remove the ampermeter and restore connection.
6. Increase instrument readings by the coefficient specified on the shunt. If it is not specified, calculate the division price independently. For example, if current of a full deviation of the indicator is equal 100 mk, and the shunt is designed for 10 A, then to each microampere on a scale there will correspond 0.1 A currents in a chain.
7. As a last resort it is possible to use the shunt without designations and any magnetoelectric indicator. Connect consistently test and model ampermeters. Connect them to the current stabilizer. Smoothly raising current from zero, achieve a full deviation of an arrow of the test device. Recognize current in a chain by the model ampermeter. Divide it into the number of divisions on a scale and by that calculate the price of one division.