How to measure frequency
August 2024
Electrical Power & Protection
Circuits and equipment may be designed to operate at a fixed or variable frequency. They may perform abnormally if operated at a different frequency than specified. For example, an AC motor designed to operate at 60 Hz operates slower if the frequency is less than 60 Hz, or faster if the frequency exceeds 60 Hz. For AC motors, any change in frequency causes a proportional change in motor speed. A 5% reduction in frequency yields a 5% reduction in motor speed.
Some digital multimeters include optional modes related to frequency measurement:
• Frequency counter mode measures the frequency of AC signals. It can be used to measure frequency when troubleshooting electrical and electronic equipment.
• MIN MAX recording mode permits frequency measurements to be recorded over a specific period. It provides the same function with voltage, current, and resistance.
• Autorange mode automatically selects the frequency measurement range. If the frequency of the measured voltage is outside the frequency measurement range, a digital multimeter cannot display an accurate measurement.
Digital multimeters with a frequency symbol on the dial
1. Turn the dial to Hz. This usually shares a spot on the dial with at least one other function. Some meters enter the frequency through a secondary function accessed by pushing a button and setting the rotary switch to AC or DC.
2. First insert the black test lead into the COM jack.
3. Then, insert the red lead into the V Ω jack. When finished, remove the leads in reverse order: red first, then black.
4. Connect the black test lead first, and the red test lead second. When finished, remove the leads in reverse order: red first, then black.
5. Read the measurement in the display. The abbreviation ‘Hz’ should appear to the right of the reading.
Digital multimeters with a frequency button
1. Turn the dial to AC voltage (AC voltage indicator). If the voltage in the circuit is unknown, set the range to the highest voltage setting. Most digital multimeters power up in Autorange mode, automatically selecting the measurement range based on the voltage present.
2. First insert the black test lead into the COM jack.
3. Then insert the red lead into the V Ω jack.
4. Connect the test leads to the circuit. The position of the test leads is arbitrary. When finished, remove the leads in reverse order: red first, then black.
5. Read the voltage measurement in the display.
6. With the multimeter still connected to the circuit, press the Hz button.
7. Read the frequency measurement in the display. The Hz symbol should appear in the display to the right of the measurement.
Frequency measurement considerations
In some circuits, there may be enough distortion on the line to prevent an accurate frequency measurement. For example, AC variable-frequency drives (VFDs) can produce frequency distortions.
When testing VFDs, use the low-pass filter AC V setting for accurate readings. For meters without the AC voltage indicator setting, turn the dial to DC voltage, then press the Hz button again to measure the frequency on the DC voltage setting. Change the voltage range to compensate for the noise if the meter allows for a decoupled frequency measurement.
Further reading:
Boiler selection for optimal thermal energy performance
Electrical Power & Protection
The changing world of boilers means companies wishing to improve their thermal energy efficiencies while containing costs and environmental impacts must make careful and informed decisions. AES’s rich pool of experience, ability to keep pace with new steam trends and technologies, and understanding of their clients’ production processes can assist clients to weigh up different options in a careful and informed manner.
Read more...
Securing Africa’s energy future starts at home
ACTOM Electrical Machines
Electrical Power & Protection
Africa’s energy demands are surging, but the current reliance on imported solar technology leaves the continent vulnerable. This is why the prospect of building inverters and lithium batteries locally, designed for South Africa’s specific needs, is so promising.
Read more...
Dry-type transformers for Dutch intake substation
Electrical Power & Protection
A data centre in the Netherlands is the site of a recent innovation on the transformer landscape, where TMC Transformers has designed, manufactured and installed dry-type transformers in a large intake substation.
Read more...
Generators: The muscle in the new energy mix
WEG Africa
Electrical Power & Protection
Contrary to their reputation as noisy and dirty, generators are a key part of modern energy supplies. Generators are reliable electricity workhorses in times of need. But they are also becoming welcome additions to modern energy mixes through efficiency improvements, noise reduction and flexible design choices.
Read more...
Doubling down on sustainability commitments: six practical solutions to meet the AI challenge
Schneider Electric South Africa
Electrical Power & Protection
The best time to plant a tree, the old saying goes, was 20 years ago, and the second-best time is today. The same concept holds true to sustainability in the data centre industry.
Read more...
Condition-based maintenance can revolutionise business continuity
Schneider Electric South Africa
Electrical Power & Protection
As businesses experience growing pressure to enhance operational efficiency and reduce downtime due to electrical failure, condition-based maintenance becomes essential for preventing unforeseen equipment breakdowns by assessing the real-time health of electrical systems.
Read more...
Ball valves and actuators to optimise HVAC performance
Schneider Electric South Africa
Electrical Power & Protection
Schneider Electric South Africa offers the full range of innovative SpaceLogic and EasyLogic ball valves and actuators. These cutting-edge products are designed to optimise HVAC system performance, ensuring comfort and energy efficiency in industrial, commercial and residential buildings.
Read more...
Power over Internet splitter for reliable power distribution
Vepac Electronics
Electrical Power & Protection
A manufacturing facility requires a stable power supply for its wireless access points mounted across the factory floor. However, these devices do not support direct PoE input. By deploying the IPS-342P PoE Splitter from Vepac, the facility can efficiently convert PoE power from the network switch into 24 V DC output.
Read more...
World’s fastest 16-bit arbitrary waveform generator
Vepac Electronics
Electrical Power & Protection
The ARB Rider AWG-5000 is the world’s fastest 16 bit Arbitrary Waveform Generator, with 6,16 GS/s real time update rate (12,32 GS/s in RF mode) and 16 bit vertical resolution.
Read more...
Wireless test tools
Comtest
Electrical Power & Protection
Fluke has on offer the Fluke 376 FC True-RMS Clamp Meter with iFlex, the most advanced troubleshooting tool for industrial and commercial electricians
Read more...
printer friendly version