LAUREL LTE Series, Руководство пользователя

Страница: 28 / 48

- 28 -
15. RTD & OHMS SIGNAL CONDITIONER BOARD
The same signal conditioner board can be configured via jumpers for four RTD types (DIN
100
Ω
platinum, ANSI 100
Ω
platinum, 120
Ω
nickel, 10
Ω
copper) or for five resistance ranges
(from 20.000
Ω
Ω
to 200.00 k
Ω
). Fixed 2
Ω or
2 M
Ω
resistance ranges can be provided by a
factory modified signal conditioner board.
All ranges are factory calibrated with calibration factors stored in EEPROM on the signal condi-
tioner board. Instrument Setup Software recognizes the board and will bring up the appropriate
menu items for it; however, it does not recognize the jumper settings. Items to be entered in
Instrument Setup Software for the input side include Mode (RTD or Ohms), Range (RTD type
or ohms range), and Scale and Offset (a calibration correction applied to resistance).
1. Use 2.5 mm (0.1") jumpers.
2. Store spare jumpers on an unused jumper post.
RTD and resistance measurement allow 2-, 3- or 4-wire hookup to compensate for lead wire
resistance. Please see Section 6 for hookup diagrams.
• In 2-wire hookup, the transmitter senses the voltage drop across the load and both lead
wires. The effect of the lead wires can be measured and subtracted by shorting out the load
during transmitter setup, as prompted by Instrument Setup software. The short should be as
close as possible to the load. Ambient temperature changes will still cause some error in the
readings -- the higher the lead resistance, the greater the error.
• In 3-wire hookup, the transmitter automatically compensates for lead resistance by mea-
suring the voltage drop in one current-carrying lead and assuming that the voltage drop in
the other current-carrying lead is the same.
• In 4-wire hookup, there is no lead wire resistance error, as different pairs of wires are used
for excitation and sensing. The sense wires only carry a few picoamperes and hence can
measure the voltage across the RTD without error.
Standard Board Modified Board E1 Jumper
Pt100, Ni120
Cu10, 20.000
Ω
0 - 200.00
Ω
0 - 2.0000 k
Ω
0 - 20.000 k
Ω
0 - 200.00 k
Ω
N/A
0 - 2.0000
Ω
N/A
N/A
N/A
0 - 2.0000 M
Ω
a
b
c
d
e
f
Connection for RTD or Resistance E2 Jumper
2 or 4 wire
3 wire none
g