Current clamp or clamp meter is an electrical measuring instrument used to measure the amount of electric current flowing in a cable.
Current clamp is considered more practical than other electric current measuring instruments because they do not require users to interfere with existing electrical circuits. The shape of the current clamp resembles crab claws with cavities in the claws.
Before operating the current clamp, you should understand the parts of the current clamp and their functions to avoid errors in operation. The parts of current clamp in general are as follows:
Clamp is a part that shaped like crab claws. Inside the clamp there is a conductor that functions to capture electromagnetic waves emitted by current flowing in the cable. The clamp itself is made of a polymer that surrounds the conductor inside.
2. Centering Marks
Centering marks are markers placed on the clamp in order to center the cable being measured against the clamp. In other words, the centering marks become a reference whether the cable is in the middle of the clamp or not.
3. Hand Guard
The hand guard is the limit at which the user’s hand is allowed to hold the current clamp. The hand guard is also used as a limitation so that the user’s hand does not touch the conductor which will cause damage to the electric current reading or may be exposed to leakage current.
4. Peak Hold
Peak hold is a feature of the current clamp that is used to hold the current reading at a certain number. This peak hold feature is mirrored into a button.
Lever is part of the current clamp that serves to open or close the jaw clamp.
In the condition where you want to insert the cable in the clamp, the lever must be pressed until the cable is in a position in the middle of the clamp, then release the lever to start reading the current. The current will not be read until the clamp position is closed.
6. Function Switch
The function switch is part of the current clamp which has a function to control the use of this tool. It contains several features such as the electric current measurement function, the voltage measurement function and the cable resistance measurement function.
Please note in advance that the current clamp does not only function to measure electric current, but also have the 3 functions mentioned earlier.
The electric current measurement function is to find out how much current flows in the cable, in this function there are several measurement ranges that can be selected based on the estimated current flowing in order to get more accurate readings.
The voltage measurement function is intended to measure the voltage of the cable being measured, it can measure 3 or 1 phase, the measurement range is also provided to make the reading more accurate. Meanwhile, the resistance measurement function serves to detect cable connections, whether there is a line break or not.
7. On/Off Switch
On/off switch is a switch to turn on and off the current clamp. This switch is in one place with the function switch.
8. DC A Zero Adjustment Switch
Has a function as a calibration feature when measuring DC current. Additionally, the current clamp can also be used to measure DC current.
The display is part of the current clamp which serves to show the results of the current clamp measurement. The display can be a digital or analog display, depending on the type of current clamp used.
10. DC or AC Switch
DC or AC switch is a switch that functions to switch the current clamp reading function. If it is used to measure DC electricity, then position this switch in the DC position, if it is used to measure AC electricity, then position this switch in the AC position.
11. Common Terminal (COM)
COM is the terminal for the supplied black wire. If you take measurements other than current measurements, then this cable must be used.
12. 600V Max
Is a limitation of the use of current clamp. This means that the current clamp can only be used to measure electricity at a cable voltage with a 600 V source. This value can be different for each current clamp.
13. V Hz
Is a terminal for the red wire, located next to the COM socket. The red wire must be inserted into this terminal if you want to measure DC/AC voltage, resistance, continuity test, diode test and frequency measurement.
How Current Clamp Work
The working principle of the current clamp is quite simple, it only utilizes magnetic induction which occurs when an electric current flows in a conductor.
The magnetic induction is captured by the current clamp through the conductor contained in the claws and converted into an electric current to be read. This working principle is the same as an isolator transformer with an ampere meter.
The explanation above may differ from other explanations depending on the type of current clamp and the brand used.