Temperature Corrections

*TB 43-177

Vxi = Vref + vi + tc

a. Temperature corrections must be computed for

both the reference and working group when the

Where Vxi is the computed voltage value for the i

temperatures of the enclosures at the time of test are

cell in the working group; Vref is the certified mean

different from their nominal temperatures.

These

voltage of the reference standard cell group at nominal

corrections may be closely approximated by the following

temperature, vi is the measured differences (small

equation.

between cells obtained from the measurement design,

Tc = ∆t Ct

and tc is the net temperature correction for both the

reference and working enclosures.

Where:

Tc is the temperature correction

∆t is the actual temperature minus

B-5.

The measured data from the observation sheet

nominal temperature

is substituted into the following equations to obtain the

Ct is the temperature coefficient

value for each cell of the working group at nominal

at the nominal temperature

temperature:

The most common nominal temperatures for standard

(obs) + (obs10) - (obs1) - (obs2) + tc

cell maintenance are 28°C, 30°C, 32°C, and 35°C.

Cell A =V ref +

Temperature coefficients at these temperatures are

given below.

V ref + (obs11) + (obs12) - (obs3) - (obs4) + tc

Cell B =

C28 = -54 µV/°C

C30 = -57 µV/°C

C32 = -59µV/°C

V ref + (obs13) = (obs14) - (obs5) - (obs6) + tc

Cell C =

C35 = -62 µV/°C

V ref + (obs15) + (obs16) - (obs7) - (obs8) + tc

b. For an example, consider the data in figure B-

Cell D =

1. Nominal temperature of the transport standard is

32°C. Measured temperature is 32.004°C.

Vx (Mean of UUT Group) =

Tc = ∆t Ct

Then

(cell A)+(cell B)+(cell C)+(cell D)

Tct = .004 x (-59)

Tct = -.236 µV for the transport standard

B-6.

To obtain the value for each cell of the

Nominal temperature of the lab standard is 32°C.

reference group, substitute the measured data from the

Measured temperature is 32.009°C.

V x from 4 above into the

observation sheet and

following equations:

Tcl = ∆t Ct

Then

Tcl = .009 x (-59)

Tcl = -.531 µV for the lab standard

V x + (obs 1)+(obs 8)-(obs 12)-(obs 13) -tc

Cell 1 =

c. The correction tc used in this technical bulletin

corrects voltages to the nominal temperature of both

V x + (obs 2)+(obs 3)-(obs 14)-(obs 15) -tc

Cell 2 =

enclosures and is computed as follows:

tc = Tct - Tcl

V x + (obs 4)+(obs 5)-(obs 9)-(obs 16) -tc

Cell 3 =

For this example:

tc = -.236 - (-.531)

tc = +.295 µV

V x + (obs 6)+(obs 7)-(obs 10)-(obs 11) -tc

Cell 4 =

This is the quantity that would be substituted in the

B-7. Temperature Corrections

equation (B-4 above) for tc.

B-8.

Sample computations for the data in figure B-1.

B-3