Agilent Technologies 34401A manual Measurements Below Full Scale, High-Voltage Self-Heating Errors

Chapter 7 Measurement Tutorial

Measurements Below Full Scale

Measurements Below Full Scale

You can make the most accurate ac measurements when the multimeter is at full scale of the selected range. Autoranging occurs at 10% and 120% of full scale. This enables you to measure some inputs at full scale on one range and 10% of full scale on the next higher range. The accuracy will be significantly different for these two cases. For highest accuracy, you should use manual range to get to the lowest range possible for the measurement.

High-Voltage Self-Heating Errors

If you apply more than 300 Vrms, self-heating will occur in the multimeter’s internal signal-conditioning components. These errors are included in the multimeter’s specifications. Temperature changes inside the multimeter due to self-heating may cause additional error on other ac voltage ranges. The additional error will be less than 0.02% and will dissipate in a few minutes.

Temperature Coefficient and Overload Errors

The Agilent 34401A uses an ac measurement technique that measures and removes internal offset voltages when you select a different function or range. If you leave the multimeter in the same range for an extended period of time, and the ambient temperature changes significantly (or if the multimeter is not fully warmed up), the internal offsets may change. This temperature coefficient is typically 0.002% of range per °C and is automatically removed when you change functions or ranges.

When manual ranging to a new range in an overload condition, the internal offset measurement may be degraded for the selected range. Typically, an additional 0.01% of range error may be introduced. This additional error is automatically removed when you remove the overload condition and then change functions or ranges.

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