Setra Systems 205-2 Operating Instructions

159 Swanson Road, Boxborough, MA 01719/1-800-257-3872, (978)263-1400
SSO251REV C 11/8/12
OPERATING INSTRUCTIONS
MODEL 205-2 PRESSURE TRANSDUCER
FOUR-WIRE, VOLTAGE OUTPUT
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 ranges and dimensions are reported on the specifi-
cation bulletin for the transducer.
INSTALLATION
Do not use in ambient conditions corrosive to polyvinyl chloride (cable) or stainless steel, submerged
in liquids, subject to spray or drip, or in a high vibration environment. The 205-2 Series is very slightly
sensitive to acceleration in the pressure fitting axis, less than 0.05 psi/g typical. Factory calibrated in the
vertical position, with pressure port downward, this position often minimizes damage from dripping of
pressure system piping.
Installation of pressure fitting:
For very high pressure use of sealant such as Loctite hydraulic sealant is suggested.
For other pressure ranges, standard sealants such as Teflon tape generally are satisfactory.
For the most sensitive pressure ranges, excessive high torquing of a metal pressure fitting may
cause a slight zero shift which may be trimmed out using the zero adjustment. Use of plastic
fittings often shows no noticeable zero shift. The torquing effect does not appreciably affect
linearity or sensitivity. Use the wrench flats on the 205-2 when attaching to fittings.
ATMOSPHERIC REFERENCE (Gage pressure transducers only)
Lower range units are subject to excessive thermal zero shift unless vented to atmosphere. The electrical
cable provides this equalization vent.
ELECTRICAL CONNECTIONS:
CABLE LEAD
Red
Green
White
Black
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 output lead, but must not be commoned or grounded at
more than one point. The negative output lead is approximately 1.66 VDC above the negative excita-
tion lead. The positive output lead is at this same 1.66 VDC common mode voltage plus the output
signal from applied pressure (thus goes from approximately 1.66 VDC up to 6.66 VDC above the negative
excitation).
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 the shield to white or shield to black
leads. Best shielding against noise will be obtained by connecting the shield
and negative excitation (black) 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 length) may introduce enough cable capacitance
FUNCTION
positive excitation
positive output
negative output
negative excitation
case