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Model 300 Level Indicator

The Model 300 is a microprocessor based level / weight indicator.

A local display is provided by means of a red LED  bar graph, with 2% increments.

Remote level data is provided by an isolated 4-20mA current source, an RS 485 port is also available for digital data transmission.

The Model 300 can accept the output from 3 and 4 wire style load cells / strain gauges.

It is an ideal instrument for use with “bolt on” and “press in” type sensors commonly used to instrument  existing tanks and silos.

MODEL 300 - TECHNICAL SPECIFICATIONS
MODEL 300 INDICATOR SUITABLE FOR USE WITH FOIL BASED STRAIN GAUGES AND SEMICONDUCTOR BASED STRAIN GAUGES (4-WIRE AND 3-WIRE).

Level control using direct support (load cells) or stress measurement (bolt on/press in) technology, have become industries preferred method, for the following:-

No inaccuracies caused by material profile.
Weighing provides continuous level control.
No performance degradation caused by material build up on sensors. Sensors are fitted outside the tank and therefore not subject to hostile environments often found inside tanks and silos, especially when being filled.
Dust in the tank/silos atmosphere cannot blind the system.
Load cells etc are passive devices which do not emit annoying sound waves, radio waves or laser light, which can be irritating to operations staff.
The Model 300 has been provided with standard features that other manufacturers call options. The combination of a 20 bit Sigma Delta Analogue to Digital converter and selectable amplifier gain, enables the instrument to accommodate a wide range of input signals. These features together with the ability to accept both full - bridge and half bridge type load cells and strain gauges, make the Model 300 a truly versatile instrument.
The built in functions such as zeroing, calibrating,and the programming of set points are simply accessed and performed through an integral four key, keypad.
The Model 300 level controller is a “state of the art” device, utilising an embedded Motorola HC11 microprocessor as the main processing element.
The microprocessor is watchdog equipped. Providing the user with “get up and go” after a program disturbance.
The power supply is rugged and uncomplicated and fitted with line filters. For applications where the mains power is exceptionally noisy, Web-Tech can optionally supply proprietary line filters.
Augmenting the the built in electronic robustness of the electronics, is the provision of an IP65 /NEMA 4X rated enclosure, made from moulded fibreglass polyester and incorporating patented quick release latches and piano style hinges.
Moulded fibreglass polyester has outstanding chemical and temperature resistance and exhibits excellent weatherability and physical properties. Oil resistant “O” ring gasket with tongue and groove construction combine to produce a consistently repeatable seal.
An optically isolated, parallel, analogue to digital converter provides a full 12bit output to the remote current driver.The current loop output is internally generated,and is capable of driving into a maximum of 800 Ohms. A light emitting diode fitted to the main processor PCB, provides visual indication of current loop failure.
Local display is by means of a vertical red LED bar graph, with a resolution of 2%.
Signal dampening is provided for bins and tanks with internal agitators.
A systems status relay has been provided, allowing PLC /DCS’s to poll status of the instrument.
All field programmed parameters are stored in non volatile memory, so power outs don't require the user to re-program.
The Model 300 is switch selectable 120/240VAC dual voltage operation.
High and low relay outputs have been provided for those customers without access to a PLC/DCS.
Material build-up inside the bin is cancelled by means of the “Autozero” function.