742A Series
Instruction Manual
Figure 5 shows a graph of the value of the 742A-1 represented by the sample
temperature characterization chart (Table 4). To illustrate use of the formula,
calculations for resistance at 20
°
C and 26
°
C are shown. You can see that using
the formula shown with alpha and beta you get the same value as in the
characterization table.
Figure 5. Graph of Resistance VS. Temperature for Sample 742A-1
R
t
= R
23
[ 1+
α
(t - 23) +
β
(t - 23)
2
]
At
= 20
°
C,
R
20
= 1.00000010 [ 1 + (-0.09 E-6) (-3) + (-0.034 E-6) (-3)
2
]
= 1.00000010 (1.0000003 – 0.0000003 )
= 1.00000010 (1.0000000 )
= 1.00000010
Ω
R
t
= R
23
[ 1+
α
(t - 23) +
β
(t - 23)
2
]
At
= 26
°
C,
R
26
= 1.00000010 [ 1 + (-0.09 E-6) (3) + (-0.034 E-6) (-3)
2
]
= 1.00000010 (1 - 0.0000003 – 0.0000003 )
= 1.00000010 (1 - 0.0000006 )
= 1.00000004
Ω
Storage Temperature Range
To maintain accuracy within the specified limits, do not subject the 742A Series
to temperatures below 0
°
C or above 40
°
C. If exposure to temperatures outside
this range is unavoidable, you can minimize the adverse effects by doing the
following:
•
Keep the standards in the optional transit case (Option 742A-7002). The
transit case is insulated and helps protect the standards during short-term
temperature extremes.
•
Keep exposure to temperature extremes brief.
8
