FEATURES AND BENEFITS
• Two or Four Wire versions
available - Simple, low cost, installations.
• Operates on
Admittance Principle - Minimizes error due to material build-up on probe.
• Reverse
Polarity, Lightning and EMI Protection - Tolerates long-lead wire runs
without problems.
•
Non-interacting and Wide Adjustability of Zero and Span - Simplifies
initial calibration.
• CSA Certified
Explosion-Proof and NEMA 4 Enclosure - Usable in Hazardous and Water-tight
areas.
• CSA Certified
Intrinsically safe models when used with approved barriers.
• Plug-in
Circuit Boards - Ease of maintenance.
GENERAL DESCRIPTION
The Robertshaw Model 167 is an RF Capacitance to Current
transmitter producing a standard 4-20 mADC current output signal directly
proportional to the input capacitance. The Model 167 represents a totally
new concept in capacitance instrumentation and features a patented circuit
design to eliminate the effects of sensing probe coatings and provide a
true level signal. This circuit design operates on the admittance
principle such that all parameters are taken into account, such as
susceptance and conductance.
The Model 167 offers various supply configurations. The
Model 167-A is a two-wire system operating on any DC voltage ranging from
17 VDC to 35 VDC maximum. This system allows for simple, inexpensive
installation since only two standard wires are used to power the
instrument and also carry the output signal. The Model 167-B/C series are
four wire instruments utilizing 120 VAC or 240 VAC supply power.
Standard features of the Model 167 include the "AntiCoating"
feature, plug-in circuit boards for ease of maintenance when required, EMI
suppression, lightning protection and reverse polarity protection on the
two-wire version. The Model 167 is housed in an explosion-proof cast
aluminum enclosure suitable for hazardous areas or Water-tight NEMA 4
locations. Due to the very low energy levels imposed on the sensing probe,
as well as the low stored energy within the circuitry, the Model 167-A
also qualifies as intrinsically safe when used with an approved safety
barrier.
