What Is a Current Logger?
A current logger is a device that records current values while measuring them. Current loggers are sold as products by manufacturers of measuring instruments and store current values in memory while measuring and displaying them.
The unit of current is mainly A (ampere) or mA (milliampere), which is displayed on the interface panel. Some products offer a choice of sampling rates, with some having sampling rates as high as 100 times/second (100 Hz). Various types of power loggers are available, and there is a need to select the appropriate instrument depending on the desired measurement accuracy.
Uses of Current Loggers
Current loggers are measuring instruments used primarily for current measurement. Handheld loggers are also available, and in most cases are carried and used.
- Confirmation of energization in PC repair
- Pre-installation check of semiconductor devices in board mounting
- Maintenance of production equipment
- Confirmation of commissioning of electrical work
- Temporary measurement for production machinery management
- Monitoring of lithium-ion batteries (cell-by-cell )
Principle of Current Loggers
Current loggers are divided into several parts: the clamping section, transmission wiring, interface panel, and recording media. The principle of the clamping section is the same as that of a current transformer. The main part is an arc-shaped iron core that can be opened and closed by hand. It clamps the measuring current path as the primary winding and conducts the current to the transmission wiring as the secondary winding.
The transmission wiring is a common copper wire covered with a vinyl or other sheath. Some have a dedicated connection plug at the end, while others are pulled directly into the logger. Measured values are checked and set via the interface panel.
Some devices also allow the sampling rate, recording format, etc. to be set via this panel. Increasing the rate allows for more detailed recording, but it does not allow for long-term record keeping. Measurement results are written and stored on the recording media as needed.
USB flash memory or SD cards are used as recording media. CSV or txt files are often used as the output format. The clamp section above can only measure AC power.
For DC power supply measurement, a Hall element or similar device using the Hall effect is used. The Hall effect is the principle that an electromotive force is generated when a magnetic field is generated perpendicular to a conductor through which a current flows. Hall elements use this Hall effect to convert the magnetic field generated around an electric current into a voltage.
Current loggers using a shunt resistor may also be used to measure precise current values. A shunt resistor is a low-resistance resistor that is inserted in series with a shunt resistor in the measurement circuit. The current is calculated by measuring the voltage at both ends of the shunt resistor.
Hall elements and current transformers can measure current while the circuit is energized, but shunt resistors require the measurement circuit to be opened once. Because of their versatility, current loggers that use Hall elements or current transformers as the sensing element are generally used. The unit of current is A (ampere). Units used for measurement include kA (kiloampere), A (ampere), and mA (milliampere).
Since current loggers use analog signals as input data, noise may cause inaccurate measurement results. To improve detection accuracy, it is important to take measures, such as noise elimination of the wiring path, to avoid noise.
Other Information on Current Loggers
Origin of Current Logger
A log is a word that means a daily record, and the object that stores the record is called a logger. For example, a blog is an abbreviation of a weblog, which means to keep a diary on the web. Thus, a current logger is an object that records electric current.