The Working Principle of Clamp Meters
1. Structure of magneto electric clamp ammeter
The magneto electric clamp current meter mainly consists of a special current transformer, a rectified magneto electric current meter, and internal components
Composition of lines, etc. The commonly used models are T301 and T302. The T301 clamp ammeter can only measure AC current, while the T302 can measure both AC current and AC voltage. There are also pocket clamp ammeters for both AC and DC, such as MG20, MG26, MG36, and other models. The appearance of T301 clamp shaped watch is shown in Figure 1. Its accuracy is level 2.5, with current ranges of 10 A, 50 A, 250 A, and 1000 A.
2. Working principle of clamp ammeter
The working principle of a clamp meter is based on the working principle of a current transformer. When the clamp meter wrench is tightened, the iron core of the current transformer can be opened, and the wire of the measured current enters the clamp as the primary winding of the current transformer. When the wrench iron core is loosened and closed, an induced current is generated on the secondary winding according to the principle of the transformer, causing the ammeter pointer to deflect and indicate the value of the measured current.
It is worth noting that since its principle is based on the principle of a transformer, whether the iron core is tightly closed and whether there is a large amount of residual magnetism has a significant impact on the measurement results. When measuring small currents, it will increase the measurement error. At this point, the tested wire can be wound around the iron core a few more times to change the current ratio of the transformer and increase the current range. At this point, the measured current Ix should be:
