The principle and application of clamp ammeter
Clamp ammeter, also known as clamp meter, is a special electrical instrument for measuring alternating current. It is generally used to measure current when the circuit is not disconnected. Multifunctional digital display or pointer display instruments are generally used now. However, the widespread use of digital clamp ammeters adds a lot of multimeter functions to clamp meters, such as voltage, temperature, resistance, etc. Different functions can be selected through the knob, and the use method is almost the same as that of ordinary clamp meters. General purpose digital multimeter.
Clamp ammeter, as the name suggests, its measuring mechanism is like a pair of pliers, which can be opened and closed. When measuring, open the mechanism, let the wire pass through the jaws, and then turn off the measuring current.
Clamp-on ammeters measure AC and DC current on low-voltage lines without interrupting load operation.
1. The clamp meter made of electromagnetic current transformer can only measure AC current, not DC current
2. The clamp meter made of Hall current sensor can measure AC and DC current.
5 Main Uses of Clamp Meters
Purpose 1: Measure three-phase three-wire loop current and three-phase four-wire neutral current
Clamp meters typically measure current in a single wire. When measuring the three-phase three-wire load current, if two wires are clamped at the same time, the indicated current value should be the current of the third wire.
The three-phase four-wire neutral wire current measurement method is the same as the three-phase three-wire circuit current measurement method, and the three-phase wires are clamped at the same time. The current value displayed at this time is the current value of the neutral wire.
Application 2: clamp meter to measure small current
The clamp meter measures small current, even if the gear is adjusted to the minimum gear, the reading is still not very accurate. Therefore, it is possible to wrap a wire around the clamp arm and read the current value. Then divide the current reading by the number of turns to get the actual small current value.
Use three: Determine the name of the current in the line to determine whether the equipment is operating normally. It needs to be determined according to the current measured on site. So it's important to determine what current it is.
Purpose 4: Measure the no-load current of a motor without a nameplate to determine the rated power
Estimation formula: Divide the no-load current by zero to find the power close to the level.
The steps are as follows: Measure the no-load current value I of the motor, according to the empirical formula: p=I/0.8
Purpose 5: Measure the no-load current of a 380V welding machine without a nameplate to determine the apparent power S
Estimation formula: The capacity of the 380 welding machine is equal to the no-load current I multiplied by 5.
