Fail-safe operation of electrical appliances depends on the voltage in the network as a whole and in certain areas. The state of the wiring also plays an important role. Checking may be by a device called a multimeter. Figure 1 shows how a digital multimeter.
Each standard unit facilitates the measurement of the following parameters:
- DC voltage,
- AC voltage,
- alternating current,
- continuity (using the buzzer).
Multimeters also sometimes able to help measure the capacitance or frequency diode and conduct tests.
Setting up the device
Range measurement voltage values, whether the current set resistance ranging disk rotation. At the same time it is selected and the parameter to be measured. If the device is unable to automatically select, each function will have several ranges.
How to measure voltage using a multimeter
It is very convenient to use the device when on one wire will clamp "crocodile", and the second regular probe. This will free up one hand.
- Turn off power when there is a danger of shorting circuit due to closely spaced contacts or terminals.
- Insert the black ground wire to the nest "com", and the red jack labeled V, or Ω. There may still be a diode symbol.
- Rotate the dial to select DC or AC current range and to ensure maximum accuracy. When alternating current is not necessary to follow the polarity probes.
- To measure the voltage meter to be connected in parallel to a voltage source, a load or any two points in which the measurement should be carried out. Polarity when DC is important, but if you mix up the arrow just go away in the "minus". The absolute value of the instrument will show the voltage.
5. Touch the black probe and connect the "crocodile" to the first point.
6. Turn on the power.
7. Touch the red probe to the second point of the circuit under test.
8. Take the readings.
We measure the amperage
current measurement takes place anyway. Current is the flow of electrons. Therefore, the simplest way to determine the level of current flowing will arrange a gap in the circuit which connects in series multimeter.
To make the measurements were correct, it is necessary that the resistance was minimal. After all, with a resistance of 1 ohm when a current of 1 A, the error will be 1 V. For low-voltage circuits is a lot, and all multimeters have much less resistance.
current measuring sequence:
- Black probe Insert a "com" and the red socket for current measurement.
- Select the correct measuring range. It must exceed the maximum expected value of the current strength.
- Probes, connect the device to the chain and take the necessary measurements. Many networks have special terminals for connection of measuring devices.
To measure must be disconnected and the circuit element resistance test it multimeter probes connected in the sockets "com" and "Ω", as shown in Fig. 5.
Digital multimeter is a useful tool for measuring voltage, current and resistance. Some of them provide an opportunity to test diodes, transistors and capacitors. They can also be used to verify the integrity of the wiring and fuses.