Setra System Model 270 - Manual

Operating Instructions
Model 270 Pressure Transducer
General Information
Your Setra transducer has been carefully calibrated before shipment to you, and it should be handled with
the same care given any precision instrument. Pressure range and dimensions are reported on the
specifications bulletin for the transducer.
Ambient Conditions
Do not use in ambient conditions corrosive to anodized aluminum, or submerge in liquids, subject to spray
or vibration environment.
Electrical Connections:
Standard
“Belden” Cable Lead Optional
Function (#8723 Grey Cable) “Tensolite” Cable Lead
Positive Excitation Red White
Positive Output Green Yellow
Negative Output White Brown
Negative Excitation Black Black
Case Shield Shield
Electrical
The electrical circuit is equivalent to a 4-terminal network which can be grounded at only one point, either
at the negative excitation or the negative signal output lead, but must not be commoned or grounded at
more than one point.
The pressure transducer must be operated with the case connected either to the negative excitation
terminal or to the negative output terminal. Failure to do this may result in damage to, or unsatisfactory
operation of the unit. This connection may be made by connecting shield and black (negative excitation)
leads or alternatively by connecting the shield and negative output signal leads together. Best shielding
against noise will be obtained by connecting the shield and negative excitation leads. Circuit is reversed
voltage protected for at least 5 minutes. Internal transient suppression network is provided for short
duration transients to 150 volts.
In some instances, use of long cables (several hundred feet long) , may introduce enough cable capaci-
tance into the output circuit to cause output oscillation. If encountered, this oscillation may be eliminated
by connecting a 100 ohm resistor (1/8 watt or larger) in series in each of the output leads at the end of the
2 foot transducer cable. These series resistors of course add to the output resistance.
Adjustments (with cover removed)
CAUTIONS: 1. Before making any adjustments, determine which circuit board diagram on
Page 2 matches the circuit board in your transducer.
2. Turn off excitation power during cover removal or replacement.
3. Touching any adjustments other than zero or span may necessitate
recalibration and voids the warranty.