Product Overview - Advanced; Pro-Guard - Bindicator VRF II Series Installation & Operation Manual

PRODUCT OVERVIEW - ADVANCED

Figures 3 and 8 show the electronics of the integral and remote versions of the VRF II Series respectively. The
figures show the location of the electrical connections, dip switches SW5, two rotary switches SW3 and 4,
and the Power and Alarm LEDs. The settings of the VRF II Series are controlled by SW3 through 5 as shown in
Figure 12.
Figure 12: Switch Functions

PRO-GUARD

®
The VRF II Series has the ability to ignore the effects of coatings that can adhere to the sensing probe. In most
applications, a certain amount of material that is being sensed will adhere to the sensing probe after a period of
time. This can be due to the nature of the material itself or condensed moisture that can cause dry material to
bond to the probe's surface.
Pro-Guard allows the VRF II Series to disregard the effects of probe coating and only indicates that material is
present when the actual bulk material (either dry or liquid) comes in contact with the probe.
The drive current to the Pro-Guard electrode is at the same frequency and polarity as the probe. When a coating
forms on the probe, the VRF II Series current from the Pro-Guard tends to saturate that portion of the built
up material near the wall so that little or no current can flow from the probe to the wall. When the actual bulk
material in the vessel fills to the point where it touches the probe, current from the probe will flow around the
saturated region and indicate material presence.
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VRF180913 Rev. A