You will need
  • tester;
  • - the grid and the consumer.
To determine the EMF at the power source, connect the tester to its terminals. On the display appears the value of the voltage. When setting up the device first, set it on the highest voltage, then gradually increase the sensitivity to the device is not out of order. When measuring DC current, make sure to set this setting on the device and observe the correct polarity connection. When measuring voltage in AC, polarity does not matter.
When measuring the EMF of the AC source, keep in mind that the tool displays effective voltage value, which performs work by transferring a charge. The amplitude of the voltage find by multiplying the measured value by the square root of 2. For example, if the tester showed in the home network 220 In, it is the effective value of the voltage. Then the amplitude value will be 220*√2≈311 V.
When measuring voltage on any consumer tester is in the measurement mode, this value connect to its terminals. Then connect the consumer to the network. For DC polarity, and amplitude effective value of the AC voltage count by the procedure described above.
If you can not measure the voltage directly, calculate it. Measure the current in the network, and the total load resistance connected to the current source. Find the voltage U by multiplying the value of current in amperes I electric resistance R (U=I*R). For example, if the current network is 2 A, and the total resistance of 140 Ohms, the voltage in it will be equal to U=2*140=280 V.
To find the EMF current source, amperage, find out in addition to resistance part of the circuit the internal resistance of the current source, r. Then, to determine the EMF of the current source in the network, find the sum of the resistances and multiply it to the current EMF= I*(R+ r). For example, if in the same example, the internal resistance of the current source 20 Ohms, EMF=2*(140+20)=320 V.