Multimeters.

A multimeter can be used to measure a wide range of electrical properties. As multiple measuring devices, they combine several measuring functions in one device. These range from basic measurements of electrical variables to highly specialised measurements with the corresponding accessories. These are the most common measurements performed using a multimeter:

• Voltage measurement: Measures the electrical voltage (in volts) between two points in a circuit.
• Current measurement: Measures the electrical current (in amperes) flowing through a part of the circuit.
• Resistance measurement: Measures the electrical resistance of a component in the circuit. It is usually combined with a continuity test.
• Continuity test: Checks whether there is a connection between two points by triggering an acoustic signal if a current flow is detected between them.
• Diode test: Determines whether a diode works in a circuit and in which direction it conducts current.
• Capacitance measurement: Measures the electrical capacitance of a capacitor.
• Temperature measurement: Measures temperatures using special temperature sensors or probes.

There are various types of multimeters that differ in design, function and performance. The two most common designs are described below:

Hand-held multimeter 

A hand-held multimeter is a portable measuring device for electrical measurements. It consists of a display on which the measured values are shown and a rotary switch or buttons for selecting various measurement parameters such as voltage, current and resistance. Some devices have additional functions, e.g. continuity test, capacitance measurement or diode test. Hand-held multimeters are designed for use in both professional measurement and electrical engineering and for hobby use. Hand-held multimeters can be analogue or digital. Digital multimeters (DMM) are the most widely used and generally offer higher accuracy, better readability and additional functions compared with analogue devices. Analogue multimeters are more expensive and much more sensitive to shocks than digital multimeters. However, analogue multimeters can be of interest with ambiguous and changing measured values, as they allow better observation of the measurement results with regard to trends..

Bench multimeter (Desktop multimeter)

A bench multimeter is a stationary measuring device, usually mounted in a housing, which is designed for use on a table or workbench. Desktop multimeters are first choice when precise measurements and extensive functions are required – for example in laboratories, industrial environments or educational establishments. They usually have numerous measurement inputs and interfaces so that the measuring device can be integrated into test and measurement data acquisition systems without a tangle of cables on the front. Bench multimeters with built-in memory allow data logging without connection to a measurement data acquisition system or computer.

Hand-held multimeters are particularly attractive due to their compact design. They are sturdy, easy to transport and thanks to their battery operation can be used independently of a stationary power supply. Hand-held multimeters are beginner-friendly and ideal for mobile use in various working environments. In addition, hand-held multimeters are inexpensive and are therefore part of the basic equipment of workshops and service technicians.

Simple multimeters are available for less than 10 euros. High-quality devices for experts, on the other hand, cost several hundred euros. The price depends on the manufacturer, model, design and range of functions. Depending on the price range, such devices can also be used to test frequencies, pulse and duty cycles as well as diodes. High-quality multimeters with the appropriate adapters can also be used to measure additional variables such as temperatures, speeds, sound levels and illuminance levels.

The choice of a multimeter is influenced by various factors. It is important to accurately determine all the individual requirements and the intended use to ensure that the chosen device offers the required functions and specifications. 

These include:

• Measurement requirements: What types of measurements do you want to perform (voltage, current, resistance, capacitance, temperature, or other specific parameters)?
• Accuracy and resolution: Check the specifications regarding the accuracy class and maximum resolution.
• Measuring ranges: Make sure that the measuring ranges of the multimeter are sufficient for the expected measured values. Measuring ranges that are too large or too small can lead to inaccurate or unusable results.
• Ergonomics and operability: A high level of user-friendliness helps to avoid operating errors. Check the size of the display, the legibility of the display, the type of control elements and the general handling of the multimeter.
• Sturdiness and construction quality: Depending on where and how often you use the multimeter, sturdiness and construction quality are key decision factors. A sturdy housing and robust components prolong the service life of the multimeter, e. g. in rough industrial environments.
• Safety features: Particularly important when working with high voltages or in hazardous environments are aspects such as overvoltage protection, safety standards (e.g. CAT ratings) and shielded safety terminals.
• Advanced features: Some multimeters offer additional features such as data loggers, PC interfaces, memory functions, automatic range selection and more.

IEC 61010-1 has a significant influence on the use of a multimeter. The international standard specifies the minimum requirements for the safe use of electrical measuring, control, and laboratory equipment in order to prevent accidents or injuries. Compliance with IEC 61010-1 is also important for multimeters, especially when performing measurements on electrical circuits with different voltage levels. The standard defines four categories (CAT I to CAT IV), depending on the type of measurement and the location where the devices are to be used:

• CAT I: Circuits without direct communication with the mains, battery-powered devices, automotive technology (low voltage), protection class III devices (safety extra-low voltage)
• CAT II: Measurements on devices with interface to the low-voltage grid via mains plug
• CAT III: Measurements in building installations, sub-distribution boards
• CAT IV: Measurements at the transfer point of the low-voltage installation, e.g. main connection, meter box, domestic junction box

These four categories can be further subdivided according to their operating voltages (300 V, 600 V and 1000 V). When purchasing a multimeter, you must ensure that your device is approved for the respective measurement category. For your protection, a measuring device must not be used for a measurement category for which it is not suitable.

When buying a multimeter, there are other criteria to consider in addition to the correct measurement category. You should therefore ask yourself what measuring accuracy your multimeter needs to have. The measuring and display accuracy can be found in the data sheets supplied with the device. Another decision criterion is the display. We recommend a digital display with a good resolution so that you can make reliable statements about the measurement even under difficult weather and lighting conditions. This criterion is particularly important for those who frequently work outdoors. One-handed operation of the measuring device can also be useful under such conditions. Your measuring device should therefore be ergonomically designed and easy to handle.

You should also decide whether you need an automated test procedure and how you wish to record and analyse your measurement data. For automated processes, it is important that your multimeter has suitable interfaces.

Please note also that your multimeter has to be calibrated at regular intervals. A calibration service that is included in the purchase price saves time and money. Your multimeter should be suitable for calibration in accordance with applicable standards such as DAkkS.

The following manufacturers are among the main suppliers on the multimeter market. They produce digital multimeters, hand-held and bench multimeters as well as multimeter current clamps, among other things.

• Benning
• Chauvin Arnoux
• Flir
• Fluke
• Gossen
• GW Instek
• Keithley
• Keysight
• Metrawatt
• Rohde & Schwarz

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The recommended design of your device depends on the application. The most common types are hand-held multimeters and bench multimeters.

Your multimeter must fulfil the corresponding measurement category in accordance with IEC 61010-1 (CAT I to CAT IV).

Measuring devices that are used in the field should be shock-resistant.

One-handed operation is an advantage when working in confined spaces or in the field. Automated routines also make the measuring process easier.

If you want to record measured values over a longer period of time, a measuring device with a corresponding storage capacity is expedient.

When creating measurement reports, it is useful to be able to transfer measured values from your multimeter to other end devices.

If you want to connect your multimeter to a PC or tablet, your device should have the appropriate interfaces, e.g. USB-C, LAN/LXI or GPIB.

We recommend purchasing a protective bag or case for use in the field and for frequent transport.

Most multimeters can measure electronic variables without additional adapters. Measuring adapters are usually required for temperature or humidity measurements.

Accessories such as test leads, probes, current clamps and spare batteries can be useful additions to your measuring device.

Depending on the design, operating location and measuring task, your multimeter may require additional software and/or a measuring adapter. Most hand-held multimeters do not require any special software for the simple measurement of electronic variables such as current and voltage.