Introduction to the structure, working principle and price of clamp ammeter
When we electricians need to measure current without disconnecting the circuit, we need to use a clamp ammeter (sometimes referred to as a clamp ammeter). A clamp ammeter is an instrument used to measure the current in a running electrical circuit and is a commonly used measuring tool by electricians. Clamp on ammeters are divided into two categories: clamp on AC ammeters and clamp on AC/DC ammeters. Some can also measure AC voltage.
The structure and working principle of clamp ammeter:
A clamp type AC ammeter is essentially composed of a current transformer and a rectifier instrument. The measured current carrying wire is equivalent to the primary winding of the current transformer, and the secondary winding on the iron core is connected to the rectifier instrument. According to a certain proportional relationship between the primary and secondary windings of the current transformer, the rectifier instrument can display the current value of the measured line.
A clamp type AC/DC meter is an electromagnetic instrument that uses the measured current carrying wire placed in the clamp as the excitation coil. The magnetic flux forms a loop in the iron core, and the electromagnetic measuring mechanism is located in the middle of the gap of the iron core, which is deflected by the magnetic field to obtain readings. Because its deflection is not affected by the measured current, it can measure AC and DC currents.
Measurement principle of clamp type grounding resistance tester:
The ETCR series clamp type grounding resistance tester is a major breakthrough in traditional grounding resistance measurement technology, widely used in grounding resistance measurement of power, telecommunications, meteorology, oil fields, buildings, and industrial electrical equipment. So what is the principle of the clamp type grounding resistance tester?
Measurement principle of clamp type grounding resistance tester:
1. Principle of Resistance Measurement
The basic principle of measuring grounding resistance with the ETCR series clamp type grounding resistance tester is to measure the circuit resistance. See the figure below. The jaw part of the clamp meter is composed of a voltage coil and a current coil. The voltage coil provides an excitation signal and induces a potential E on the tested circuit. Under the action of potential E, a current I will be generated in the tested circuit. The clamp meter measures E and I, and the measured resistance R can be obtained through the following formula. R=E/I
2. Principle of current measurement
The basic principle of measuring current with a clamp type grounding resistance tester is the same as that of measuring current transformers. See the figure below. The AC current I of the measured wire generates an induced current I1 through the current magnetic ring and current coil of the clamp. The clamp meter measures I1, and the measured current I can be obtained by the following formula.
Among them, n is the current conversion ratio between the secondary and primary coils= n·I1
