Section 4
TM9211B-A-00
6 November 2013
4-1
4.0
CALIBRATION AND PERFORMANCE VERIFICATION
4.1
Introduction
The following section describes the calibration and performance verification procedures for the
9211B Series of Multi-tap DC Current Shunts. It is recommended that DC Shunt be calibrated at the
currents listed in Table 3 for each resistance values.
4.2
Calibration Overview
This calibration procedure covers the entire range of the 9211B Series of Multi-Tap DC Shunts. The
9211B Series has 9 shunt calibration resistance values with each reistance value requireing
verification at various currents. This requires the ability to generate currents up to 100 A (optinal
300 A) and measurement resistance down to 0.333333 m with uncertainties less than 20
.
The 9211B recommended calibration interval is 12 months or 1 There are two different methods of
calibration that customers may use.
Most customers prefer to utilized the 9211B as standard whose ohmic values remain within the
nonimal range. This means that the values listed for each resistance range will be within the 1 year
specification. For example, the 1 (0.1 A Range) will be within the 12 month tolerance of 0.01 %
(100 ppm). If the value would exceed this limitation, the unit would be adjusted or repaired to
return the unit back within the nominal range.
The second optional method is to use the actual calibrated value of each range and use this
characterized value vs the nominal value of the standard. Using the same 1 value (0.1 A range)
above as an example. Say this value drifted at a upward rate of 15
per year. In approximately
7 years, this unit will have drifted 105
or 5
greater than the nominal tolerance of
100
. Rather than have this value adjusted back to within the nominal value of 1 ± 0.01 %,
the customer uses the value obtained each year and verifies that this value remains within 0.01 %
of last calibration.
It is up to the individual customer to determine which method they will incorporate within their
calibration procedure. The calibration process to determine the validity of the UUT measurement,
regardless of the applicaton philopsy they will use, is exactly the same for either method.
The two calibration processes and tables are provided. Paragraph 4.6 and Table 4 are used if the
nominal calibration process is used. Paragraph 4.7 and Table 5 are used if the customer is using the
drift of the unit vs nominal value.
4.3
Calibration Interval and Performance
It is recommended that the 9211B series be calibrated or verified at
recommended 1 year interval. As with all Standards that have resistance elements, it is highly
recommended that past history be used to determine drift rates and allow user confidence that the
unit will remain within calibration for the next calibration period.
Summary of Contents for 9211B Series
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