Science: Technology
Low Cost Alarm   (0)  [vote for, against]
Move towards old age system but it is workable !

Normally for any parameter measured in field & indicated in some control room, separate instrumentation is required for indication & alarm.

For example consider oil level measurement in tank located 100 metre away from control room by means of ultrasonic transducer, signal conveyed to control room & displayed by means of analog scale-pointer arrangement. Now for alarm, separate instrumentation would be required (cabling, signal conditioner/ distributor etc.etc.).

The proposed idea is to put an inexpensive electric bell (or similar sort of inexpensive buzzer) next to above analog indicator. When pointer moves beyond predetermined limits, a suitably thin wire (that would practically not resist pointer movement ) would touch a strip to close the circuit & actuate buzzer/ electric bell to prompt operator action.
-- vedarshi, Nov 15 2004

meter relay http://www.simpsone...pdfe/3300%20VDC.pdf
analog meter with adjustable relay contacts [csea, Nov 15 2004]

Baked, see [link]. Interestingly, searching for "meter relay" on Google brings up a bunch of hits about race running...
-- csea, Nov 15 2004

If you have ultasonic technology, then I don't understand the need for indicators with alarm contacts. Why don't you install a DCS or PLC system?

-- Ling, Nov 15 2004

[ling]the whole idea is based on cost reduction. if you put analog indicator in control room & proposed alarm based on pointer movement, the involved cost would be nothing compared to PLC or DCS.
-- vedarshi, Nov 15 2004

random, halfbakery