F87V reads just OPEn without the their brown Tcouple inserted. Any idea if it has an internal sensor to compare or it works otherwise?
F87V reads just OPEn without the their brown Tcouple inserted. Any idea if it has an internal sensor to compare or it works otherwise?
F87V reads just OPEn without the their brown Tcouple inserted. Any idea if it has an internal sensor to compare or it works otherwise?
It does, just short the input terminals with a wire and you can read the internal sensor.
Amazingly, all of the measurements I heard were exactly right. Imagine that? Perhaps these guys helped the Air Force sometime? :)Normally, I'd say, yep, should've been an obvious fix, except that the problem didn't present itself until there was a marked ambient temperature change. I watched the guys do the calibrations, did one myself, watched the engine run ops checks, we did everything by the book, just like we're supposed to do to keep from getting somebody killed. This is one of those cases where you expected the guys weeks/months before you to do the right work as well. And I was the only one with enough balls (e.g. brains) to think outside the box.
Yes, either you spot weld them or arc or gas weld them together, or just quick and dirty wind them together tightly. Some were stir welded together.
I used to work in a naval shipyard and remember a couple weapons systems technicians checking out some wiring on a submarine one day. One guy had the meter, while the second guy was reading the test procedure and recording the results.
"Measure from terminal 1 to terminal 7. Five volts, right?"
"Yep."
"Measure from terminal 3 to terminal 12. Zero volts, right?"
"Yep."
Amazingly, all of the measurements I heard were exactly right. Imagine that? Perhaps these guys helped the Air Force sometime? :)
Yep, that's the military, they have reams of procedures and check lists for everything, and they never change them.
That's why companies like Fluke have to offer for example, an average responding version of the Fluke 28-II, instead of the True RMS one. Because all the procedures and values are based around old average responding meters.
Dave.
/* This program generates a table similar to the one at http://srdata.nist.gov/its90/download/type_k.tab */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
// if( t < 0ºC)
// E = coeff[0][0]+coeff[1][0]*t+coeff[2][0]*t^2+...+coeff[10][0]*t^10
// else
// E = coeff[0][0]+coeff[1][0]*t+coeff[2][0]*t^2+...+coeff[9][0]*t^9+a0*exp(a1*(t - a2)*(t - a2)).
//
// coefficients for E=f(t), E is in mV and t is in oC.
const float coeff[11][2] =
{
{ 0.000000000000E+00, -0.176004136860E-01 },
{ 0.394501280250E-01, 0.389212049750E-01 },
{ 0.236223735980E-04, 0.185587700320E-04 },
{ -0.328589067840E-06, -0.994575928740E-07 },
{ -0.499048287770E-08, 0.318409457190E-09 },
{ -0.675090591730E-10, -0.560728448890E-12 },
{ -0.574103274280E-12, 0.560750590590E-15 },
{ -0.310888728940E-14, -0.320207200030E-18 },
{ -0.104516093650E-16, 0.971511471520E-22 },
{ -0.198892668780E-19, -0.121047212750E-25 },
{ -0.163226974860E-22, 0.000000000000E+00 }
};
// Coefficients for exponential portion of equation above
const float a[] = { 0.1185976E+00, -0.1183432E-03, 0.1269686E+03 };
// Ranges for coefficients above
const float range[] = { -270.000 , 0.000, 1372.00 };
float C_to_mv (float t)
{
int k;
float mv=0.0;
if(t<range[1])
{
for(k=10; k>0; k--) mv=(mv+coeff[k][0])*t;
// mv+=coeff[0][0]; // Not needed because coeff[0][0]=0.0
}
else
{
for(k=9; k>0; k--) mv=(mv+coeff[k][1])*t;
mv+=coeff[0][1]+a[0]*exp(a[1]*(t-a[2])*(t-a[2]));
}
return mv;
}
void Create_Table (void)
{
float t;
char i;
printf("\n oC 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10\n");
printf("\n%4.0f %6.3f", range[0], C_to_mv(range[0]));
for(t=range[0]+10.0; t<=range[1]; t+=10.0)
{
printf("\n%4.0f", t);
for(i=0; i>=-10; i--)
{
printf(" %6.3f", C_to_mv(t+i));
}
}
printf("\n");
printf("\n oC 0 1 2 3 4 5 6 7 8 9 10\n");
for(t=range[1]; t<=range[2]; t+=10.0)
{
printf("\n%4.0f", t);
for(i=0; i<=10; i++)
{
if((t+i)<(range[2]+0.1))
printf(" %6.3f", C_to_mv(t+i));
else
return;
}
}
}
void main (void)
{
Create_Table();
}Hi, I am new here :)
Just watched the video and some things are not clear to me yet. Hopefully someone can help with clarification.
1. The nist tables work on assumed reference junction temp of 0, if so how do you compensate for ambient temp. Substract temp from final reading or do you take the diff in mv from ambient and measured?
2. If you use for example type J cable which I understand is Iron/Constantan to a point and from there you use a copper connector and copper wires to a temperature controller it will mess up the actual readings because of the 3rd different metal you introduce?