Setra Systems 269 Installation Manual page 2

The current flows into the + terminal and returns back to the power supply
through the - terminal (See Diagram 2). The power supply must be a DC
voltage source with a voltage range between 13.5 and 30 measured between
the + and - terminals. The unit is calibrated at the factory with a 24 VDC loop
supply voltage and a 250 ohm load.
3.90"
Turn-Down
Switch
1.30"
4.0. CALIBRATION
The 269 transducer is factory calibrated and should require no field adjustment
if mounted in a vertical position. Whenever possible, any zero and/or span
offsets should be corrected by software adjustment in the user's control system.
However, fine zero and span adjustments can be made thru a calibration secure
access key. The Model 269 transducer zero offset is trimmed in the vertical
position (pressure ports pointing upward) prior to shipping from factory.
4.1 Zero/Span Adjustments with Security Key
To make secure zero and span adjustments, remove detachable process head by
pressing and pulling on side tabs. Install calibration security key in-place of
process head. (See Diagram 3).
4.2 Zero Adjustment (Current Output)
While applying zero differential pressure, zero may be adjusted by pressing the
cal button to tare zero. If fine adjustment is needed on analog output, depress
cal button while turning the encoder.
4.3 Span Adjustment (Current Output)
Span or full scale output adjustments should only be performed by using an
accurate pressure standard (electronic manometer, digital pressure gauge, etc.)
with at least comparable accuracy to the 269 transducer. With full range
pressure applied to the high pressure port (reference port open to atmosphere),
the span may be adjusted by pressing the cal button to set span. If fine
adjustment is needed on span, and control pressure is applied at least 75% of
full range, turn encoder until target output is achieved.
4.4 Turn Down Adjustment (Option)
For units with optional turn-down gain, turn down is easily adjusted through
use of slider switch located on side of unit. (See Diagram 1)
2
Low Pressure Port High Pressure Port
.48"
2.35"
Detachable Process
Head
4.50"
Detachable
Electrical
Connector
Shield
to
Ground
- +
Din
Rail
2.90"
3.70"
Diagram 1