10.4 How to find the lead wire resistance
10-9
10.4 How to find the lead
wire resistance
When using quarter bridge 3-wire method, the lead wire resistance value at the time of initial-in and
also at the current condition can be calculated from the lead wire resistance data list and the lead
wire resistance check values using the following equation:
The lead wire resistance value “r
0
” at the time of initial-in can be calculated from the value “e
r0
” in
the lead wire resistance data list and the value “e
0
” in the initial list, using the following equation:
r
0
: Lead wire resistance value at the time of initial-in (Ω)
e
r0 :
Lead wire resistance voltage at the time of initial-in (μV)
e
0 :
Bridge output voltage at the time of initial-in (μV)
Rg : Bridge resistance (Resistance value of dummy resistance 120Ω, 240Ω, or 350Ω)
e
r0
r
0
=
× Rg
1 + e
0
- e
r0
The current lead wire resistance value “r” can be calculated from the data “e” of direct check and
data “e
r
” of lead wire resistance check, using the following equation:
r : Lead wire resistance value (Ω)
e
r
: Both-end voltage of lead wire resistance at the time of lead wire resistance check (μ V)
e : Bridge output voltage at the time of direct check (μV)
Rg : Bridge resistance (Resistance value of dummy resistance 120Ω, 240Ω, and 350Ω )
e
r
r =
× Rg
1 + e - e
r
In the compensation calculation of Comet B, the lead wire resistance at the time of initial-in is
recorded and compensated. Strain “ε” based on the current lead wire resistance can be calculated
using the following equation:
e
r0
:
Both-end voltage of lead wire resistance at the time of initial -in (μV)
e
0
: Bridge output voltage at the time of initial (μV)
e
r
: Lead wire resistance voltage at the time of checking lead wire (μV)
e : Bridge output voltage at the time of direct check (μV)
e × (1 - e
r0
) - e
0
× (1 - e
r
)
ε =
(1 + e
0
- e
r0
) × (1 – e - e
r
)
○
To use Comet A or Comet B for measurement, you must execute initial-in to
measure e
0
(initial unbalance value) and e
r
(both-end voltage of lead wire
resistance) as shown in the compensation equations. The initial unbalance
value and the lead wire resistance value (only for Comet B) are measured in
the initial-in. (If initial-in is not performed, correct measurement is not
enabled because e
0
and e
r
are not measured.)
○
Since the measurement process under Comet A and Comet B setting
includes the compensation operation, a channel wh ose sensor mode is set
to quarter bridge 3-wire is automatically set to
“Measure” mode.
Note
Summary of Contents for TC-32K
Page 1: ...O p e r a t i o n M a n u a l TC 32K HANDHELD DATA LOGGER...
Page 8: ...Chapter 12 Error Message 12 1 Explanations and countermeasures for error messages 12 2...
Page 9: ...Chapter 1 Overview 1 1 Overview 1 2 1 2 Features 1 2 1 3 Details about each part 1 3...
Page 22: ...2 5 Operation outline 2 10 memo...
Page 23: ...Chapter 3 Sensor Connection 3 1 Sensor connection 3 2...
Page 65: ...5 10 Measurement auxiliary setting 5 28 memo...
Page 78: ...6 5 Recording in data memory and CF card 6 13 memo...
Page 86: ...7 7 Remote measurement 7 8 memo...
Page 98: ...8 7 Factory setting 8 12 memo...
Page 127: ...11 4 Outside drawing 11 8 11 4 Outside drawing Unit mm...
Page 128: ...Chapter 12 Error Message 12 1 Explanations and countermeasures for error messages 12 2...