Instruments for measuring magnetic field strength include Teslameters (formerly known as gaussmeters) and fluxmeters. The Teslameter is simple to use and has high measurement accuracy. It is the most commonly used instrument for measuring the strength of a magnetic field. Therefore, the use of a Tesla meter to measure magnetic field strength (or magnetic induction) is mainly introduced.
The Teslameter is composed of a meter head and a probe. The probe is equipped with a semiconductor chip. When the magnetic force line B passes in a direction perpendicular to the major surface of the semiconductor chip and passes the current I in the length or width direction, it is perpendicular to the magnetic field and current direction. The voltage V is generated on both ends of the direction. This phenomenon is called the Hall effect.When the current I is constant, the voltage V is proportional to the strength of the magnetic field B, and the voltage V is measured. After conversion, the magnetic induction intensity value is scribed on the meter dial, and the magnetic induction intensity at the probe can be read directly.Measuring method: In order to make the position of the measuring point accurate, a measuring point model (using an organic glass plate or wood board) should be made according to the magnetic pole shape before measurement. Draw the position of each measuring point on the sample plate and drill holes at the measuring point to make the probe protrude into the hole for measurement. The measurement content generally includes the magnetic field strength of each section at different positions of the magnetic system, the magnetic field strength of each key point on the magnetic pole surface and the magnetic field strength of the space point at a certain distance from the magnetic pole on each section. For example, the measurement method of the magnetic field strength of a permanent magnet magnetic separator is as follows:
(1) Select three sections in the axial direction of the cylinder: one of them is selected in the middle, and the other two sections are respectively taken at 200mm from both ends.
(2) In each section, the magnetic field strength of several key points on the surface of the cylinder must be measured. Generally, there are 3 points in each edge of the magnetic pole and in the middle (2 points in the edge of the magnetic system is not measured), and 1 point in the middle of the gap. If the number of poles is n, then the number of measuring points N=[3n-2+(n-1)]=4n-3. For example, the 3-pole magnetic system has 9 points, the 4-pole magnetic system has 13 points, and so on.
(3) Measure 3 to 5 points at a certain distance from the cylinder surface above each key point on each section. Such as 10mm, 20mm, 30mm, 40mm, 50mm points from the cylinder surface。
(4) The average value of the magnetic field strength at each point measured on the surface of the cylinder represents the magnetic field strength at the surface of the cylinder. Similarly, the mean value of the magnetic field strength at each point of a certain height from the cylinder surface represents the magnetic field strength of the arc surface.
Before the measurement is performed, the cylinder (and magnetic system) must be set up so that the height is suitable for measurement. At this point, the magnetic system is vertically downward, but the magnetic pole is not visible outside the cylinder. The position of the measuring point is not accurate. Some iron powder may be sprinkled on the cylinder. The magnetic pole edge attracts more iron powder and the magnetic pole shape can be displayed. If there is no iron powder, you can also use iron nails to find points. The position where the nail can stand on the surface of the cylinder is the magnetic pole center (or the center of the gap). After finding the exact position, mark it with chalk or a brush, and measure it point by point.
The method of use and precautions of the Tesla meter (Gaussmeter) are described in detail in the instructions provided with the instrument and can be operated according to the instructions.