Multimeters

Standards:

Manufacturer's specifications  (e.g. Fluke, Agilent Technologies, Mastech, Amprobe, Avo, Clarke, Ethos, Iso-Tek, Keithley, Kewtech, Marksman, Metrahit, Precision Gold, Sealey, TTI, Thurby, Wavetek)

These specifications specify the tolerances and limits for various functions of the multimeters including:

• DC Voltage
• AC Voltage
• DC Current
• AC Current
• Resistance
• Capacitance
• Frequency
• Conductance
• Inductance
• Temperature
• Diode testing
• Continuity testing

Care and use

1. Always select the  multimeter that best fits the application based on accuracy, working environment and ease of use.

2. Care should be taken while using the multimeter. Should you drop or overload a multimeter, it should be re-calibrated/repaired before reusing it.

3. Ensure the leads of the multimeter are protected when not in use. If the leads are damaged this could lead to false readings and even personal injury.

4. Do not overload the ranges of the multimeter when in use. Many multimeters have current overload protection which may result in blown fuses.  Various ampages and voltages are available to suit many applications, please contact us for purchasing advice.

5. Never use a multimeter that has not been calibrated, if in doubt consult an appropriate authority.

It is highly recommended that an appropriate authority such as a UKAS approved laboratory carries out a full calibration on multimeters at least once a year. In between UKAS calibrations at a frequency based on usage, multimeters could be calibrated in-house. A typical in-house calibration would include a written procedure and an associated calibration record sheet, which would contain as a minimum, the following listed information:

Type of Multimeter (Analogue multimeter, digital multimeter, digital voltmeter, analogue voltmeter)

(a) Serial number

(b) Location

(c) Procedure number

(d) Accuracy

(e) Results

(g) Measurement uncertainty

(h) Sentence if appropriate

(i) Date and calibrators signature

(j) Traceability to National Standards

It is necessary that any person carrying out such calibration work should have received appropriate training and have shown the ability to be confident via a suitable training authority. Training records should be held and maintained.

Following are layouts for typical in-house calibrations for multimeters:

Calibration to be carried out in accordance with in-house procedure number .......................

Serial Number:

Make:

Calibration Date:

Sizes:

FEATURE EXAMINED         SPEC.                 MEASURED RESULTS

DC Voltage

AC Voltage

DC Current

AC Current

Resistance

The multimeter was visually inspected for damage and the following faults were noted:

MEASUREMENT UNCERTAINTY +/- 7.0 ppm + 600 µV  of reading, 200 VDC to 12020 VDC - (Applicable for UKAS calibrations only)

Source: UKAS schedule of accreditation, Calibration and measurement capability (CMC)

Calibrators Signature: ........................................

A traceability statement in this section would be required for all items and their relevant certification utilised for the calibration of multimeters.