When measuring AC power, first disconnect the circuit and then cascade the ammeter. In actual operation, it is obviously inconvenient to disconnect the line. When AC current measurement is performed without a circuit such as a distribution line being disconnected, an ammeter equipped with a clamp-type current transformer is usually used. Clamp-type ammeter is a portable instrument that can directly measure the AC current of a circuit without disconnecting the circuit. It is very convenient to use in electrical maintenance. The biggest benefit of this measurement method is that it can measure large current without turning off the circuit under test. Quite extensive.
How to correctly use the clamp ammeter measurement A clamp ammeter is a portable meter that measures the current in a circuit without disconnecting the power supply. It uses the principle of working with current transformers. When using the clamp meter E, note that the current of the circuit under test must not exceed the rated current of the clamp ammeter. Do not switch the measuring range with the measuring wire clamped during the measurement process to prevent the high voltage of the current transformer from being opened twice and the core high heat, which may cause personal accidents and damage to the clamp ammeter. The measurement should be placed in the middle of the jaws and the jaws closed tightly so that they can be measured more accurately. If the jaws are not tightly closed, the magnetic resistance of the core magnetic circuit increases, causing the core to heat up with squeaking noise. During the measurement process, the operator should pay attention to the safety distance between the person and the live part, especially in the reading, be careful that the head and the body are too close to the live part or hit the charged body, resulting in electric shock.
GB 26860-2011 "Electrical Safety Work Regulations for Power Plants and Substations Electrical Sections" stipulates that when using clamp-type ammeters, attention should be paid to the voltage rating of clamp-type ammeters. Wear insulated gloves when standing on the insulation and should not touch other equipment to prevent short circuit or grounding. Before measuring the low-voltage fuse and horizontally arranging the low-voltage bus current, the fuses and busbars of each phase should be isolated with insulating material. When observing the watch, pay attention to maintaining a safe distance between the head and the live part.
Top Ten Brand Rankings of Clamp Ammeters 1. Brand Name: Youlide
2, the brand name: Fluke
3. Brand Name: VICTOR
4, the brand name: Xin Ling
5, the brand name: Huayi
6, brand name: HIOKI
7, brand name: Agilent
8, brand name: ATTEN
9, brand name: Lei Yi
10, the brand name: Baogong
Which brand of clamp meter is easy to use? There are so many brands of clamp-type ammeters, which brand is better? According to the actual use of the situation, the market is mainly two, one is the domestic agent of foreign brands, and the other is made in China, the quality and precision are uneven, you can look at the price on Taobao.
Recommendation: I have used Fluke KLUKE's digital clamp ammeter, imported, and reliable quality.
Clamp ammeter test a variety of numerical methods and diagrams 
Clamp meter AC and DC current measurement
Clamp meter voltage measurement
Clamp meter surge current measurement
DT266 clamp meter test steps and methods of use The clamp ammeter is mainly composed of a current mutual inductance coil and a multimeter. The induced current generated by the mutual inductance coil is read by a multimeter as shown in the figure.
Now take the DT266 current clamp meter as an example to introduce its use.
1, AC current measurement
1 Turn the switch to the ACA1000A.
2 Keep the switch in a relaxed state.
3Press the trigger to open the jaws and clamp a wire. If you clamp more than two, the measurement is invalid.
4 Read the value. If the reading is less than 200A, turn the switch to ACA200A to improve the accuracy. If it is not possible to directly read in the dark due to environmental conditions, press the hold button and take a bright spot to read.
2, AC and DC voltage measurement
1 When measuring the DC voltage, the switch is turned to the ACA200A block. When the AC voltage is measured, the switch is turned to the ACV750V block.
2 Keep the switch in a relaxed state.
3 The red pen is connected to the “V/Ω” end, and the black pen is connected to the “COM” end.
4 Red and black test leads are connected in parallel to the line under test.
3, resistance measurement
1 Switch to the appropriate range of electrical blocking.
2 Keep the switch in a relaxed state.
3 The red pen is connected to the "V/Ω end, and the black watch is connected to the COM" end.
4 Red and black test pens are connected to the measured resistors at both ends. When measuring the line resistance, the line should be disconnected from the source, and the capacitor connected to the resistor should be discharged.
4, continuity test
1 switch to 200n gear.
2 red and black pens are connected to the "V / Ω end publication COM" end.
3 If the resistance between the red and black test leads is less than (50 ± 25) Ω, the built-in buzzer sounds.
Figure clamp ammeter
1-Pliers 2-Pliers Trigger 3-Holding Switch 4-Rotary Switch 5-Display 6-Insulation Test Accessories Interface 7-Common Ground 8-Voltage Resistor Input 9-Hand Strap
5, high resistance measurement
1 Turn the switch to "EXTERNALUNlT" 20MΩ or 2000MΩ block.
2 The displayed value is unstable and in a free state.
3 Test accessories 3 plugs are inserted into the 3 input jacks of the clamp meter.
4 clamp meter switch, test accessory range switch are placed in 2000MΩ position.
5 test accessory input terminal connected to the measured resistance;
6 test accessory power supply is placed in the “ON” position, press the “PUSH” button, the indicator light is on, then the display shows the measured value. If the reading is less than l9MΩ, the range of the clamp meter test accessory is 20MΩ. Accuracy.
Use a clamp ammeter to pay attention to the problem Select the appropriate range, you can not use a small range to measure large current. If the measured current is small, you can put the current-carrying wire into the jaws for several turns, but the reading should be divided by the number of coils. It is the actual current value. After the measurement is completed, the mediation switch should be placed in the maximum range position (or closed position) for the next safe use.
Do not switch the range during the measurement.
Note that the voltage on the circuit is lower than the rated value of the clamp meter. The clamp current meter cannot be used to measure the current of the high voltage circuit. Otherwise, it may cause accidents or cause electric shock.
