Seeing at a glance whether an important valve is open or closed can be crucial. Schubert & Salzer Control Systems has developed the 2040 digital position indicator to provide a totally unique on-site signalling unit. It uses a coloured light signal, visible from a distance, to show the open or closed position of a valve.
Individual coloured signals
The digital position indicator has four coloured signals, with the open and closed positions indicated by the yellow and green. By the simple press of a button, these coloured signals can now represent the end stops. In addition, when the end stops are reached, the digital position indicator outputs this as a switching signal (NPN) to the contacts on the connector plug (M12x1-5 pin).
Besides open and closed positions, the position indicator also signals maintenance information and issues related to error messages. Errors are indicated by default by a red lamp and a constant signal at the error message output (NPN). The types of errors which are signalled are:
• Stuck valves, when the lower and upper end stops are not reached.
• Wear in seals, when the lower and upper end stops are exceeded.
• The permissible temperature is too low or has been exceeded.
• The supply voltage is too low.
After installation or exchange, for example, the position indicator uses a white flashing light to indicate that it has not yet been configured with the valve.
Maintenance signals
The valve position indicator has an integral maintenance monitor. This enables all activities of the position indicator and the valve to be recorded permanently. Data recorded include:
• Hours of operation.
• Valve strokes – therefore the changes in direction.
• The cumulative path travelled by the valve (spindle in the packing).
Thus, maintenance intervals can be set according to the actual operating conditions. After set threshold values are reached, this ‘maintenance alert’ is signalled with pulsating light and issued by the error message output. The maintenance alert is self-cancelling, but repeats at set intervals if no maintenance is carried out.
The digital position indicator can be fitted quite as easily to linear and part-turn actuators.
They are fitted directly on to the valve using a standardised adapter and a sensing pin detects the stroke or angular position of the actuator and converts it into an analog signal. The sensing pin and stop are matched to the nominal size and actuator size of the valve. The electronics evaluate the analog signal of the path reading and generate the corresponding coloured light signal or appropriate error messages. In addition, switching contacts (NPN) are available for further processing in superimposed systems. Adaptation is semi-automatic needing just the touch of a button and this is completed after a few runs up to the on and off positions.
The setting of all parameters from the colour selection (RGB colour scale) to the maintenance values is done by means of a USB adapter with the DeviceConfig adjustment software (from version 7.02.00). The current software version can be downloaded free of charge. Optionally, the digital position indicator is delivered with a Bluetooth communications module so that set-up can be done wirelessly in places where access is difficult.
For more information contact Keith Hedges, Macsteel Fluid Control, +27 (0)82 575 9354, [email protected], www.macsteel.co.za
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