<8. Maintenance>
8-3
IM 01C25W05-01EN
8.3 Calibration
Use the procedure below to check instrument
operation and accuracy during periodic
maintenance or troubleshooting.
1. Connect the instruments as shown in Figure 8.1
and warm up the instruments for at least five
minutes.
IMPORTANT
1. To adjust the transmitter for highest
accuracy, make adjustments with the
power supply voltage and load resistance
including leadwire resistances set close to
the conditions under which the transmitter
is installed. In addition, place the process
connections of both high and low pressure
side on the same level.
2. If the measurement range 0% point is
0 kPa or shifted in the positive direction
(suppressed zero), the reference pressure
should be applied to the high pressure side
as shown in the Figure. (The low pressure
side is released to the atmosphere.) If the
measurement range 0% point is 0 kPa or
shifted in the positive direction (suppressed
zero), the reference pressure should be
applied to the low pressure side in the
case of a differential pressure transmitter.
(The high pressure side is releases to the
atmosphere.) In the case of a pressure
transmitter, use a vacuum pump to apply the
negative reference pressure.
P
P
V
Reference pressure
Load resistor
, 250Ω
MT220
pressure transmitter
Low pressure side
transmitter (slave)
Rc
R
Load adjustment
resistor
100Ω
Digital voltmeter
Power supply
E
7674 type
Pressure generator
Pressure source
Supply pressure
When a pressure generator
is used
When the pressure source
and pressure transmitter
are combined
High pressure side
transmitter (master)
PC/FieldMate
F0801.ai
Figure 8.1
Instrument Connections
