Setra System Model 265 - Manual (Page 2)

2
4.0. CALIBRATION
The 265 transducer is factory calibrated and should require no field adjust-
ment. Generally, the mounting position will have a zero shift effect on ranges
below 1” WC. Whenever possible, any zero and/or span offsets should be
corrected by software adjustment in the user’s control system. However, both
zero and span adjustments are accessible either on the front of the unit or by
removing the optional conduit enclosure. The 265 transducer is calibrated in
the vertical position at the factory.
4.1 Voltage Output Zero Adjustment
While monitoring the voltage between the positive output (OUT) and
common (COM), and with both pressure ports open to atmosphere, the zero
may be adjusted by turning the zero adjustment screw. (See Diagram 1 for
265
Current
Monitoring
Device
9 to 30 VDC
+
_
SPAN
ADJUSTMENT
ZERO
ADJUSTMENT
Diagram 1
Diagram 2
- COM
OUT
Power
Supply
Readout
or
DAS
+ EXC
Model
265
Voltage Circuit Diagram
CurrentCircuit Diagram
3.2 Current Output Units
The Model 265 is a two-wire loop-powered 4 to 20mA current output unit (see
Diagram 3). The current flows into + terminal and returns back to the power
supply through the - terminal (see Diagram 3). The power supply must be a DC
voltage source with a voltage range between 9 and 30 measured between
terminal + and - terminals. The unit is calibrated at the factory with a 24 VDC
loop supply voltage and a 250 ohm load.
+EXC Connected to positive terminal of DC/AC
power supply
-COM Connect as the reference for power
supply and output signal
OUT Connect to positive terminal of control
or pressure