The salient features of this level measuring instrument are as follow:
Three Element Coat Guard Technology
Can be configured either for High or Low Level point switching
Reduces the Inventory cost
Ignores material build-up on the probe
Suitable for the highly dusty environment
Fast and Easy Installation Simple Calibration
Field selectable operation logic
Provides economical solutions
Various models not required
Output: 2 sets of potential free c/o contacts rated at 5 amps, 230 V AC for non-inductive loads
Switching delay: Continuously adjustable From 1 to 20 sec. probe Free or probe covered (Optional)
Safety operation: Field selected switch over for min. or max. (FSL/FSH) switching points
Switch status display: Green LED shows Normal, Red LED shows alarm, Yellow
LED shows power on condition
The Principle of Working:
The major shortcoming of the conventional method is that after the level has once increased and then decreased, there may be a coating left on the probe sensed by the instrument as though the level is still on the probe. In our switch, a coat guard amplifier is incorporated in the circuit having its output exactly at the same voltage and phase at all times as its input.
The output is connected through the shield of the low capacitance co-axial cable to the concentric tube on the sense probe, called shield element. There is no current flow through the cable as both the elements, sense and shield are exactly at the same potential and phase at all times.
This results in no change in calibration due to coating on the probe and the temperature effect of the cable. This makes it possible to increase or shorten the cable connecting the switching unit without changing the original calibration.