Originally posted by: DTSFA
I have a normally open switch that temporarily shorts out part of a control circuit for machine to continue operation,
from a safety perspective I wish to monitor this switch in case it 'welds shut'
volts = 24v dc
current = 1A max
one switch is reed type, other is plunger type Link
apart from bespoke electronics to do this, does anyone know of safety type normally open switches
or some off the shelf solution for this problem
Which switch is in danger of welding shut? Why have you described one switch in the first part of your post then listed two types of switch in the second part? Is one switching or powering the other?
What do you want to do if your critical switch fails?
Presumably you want to make your switch fail detect completely hardwired and independent of a more complex control system (via a high impedance digital input for example).
I would ask questions like:
- Can you reduce the current in your problem switch and drive the current through a more reliable relay or solid-state relay?
- Is there inductance in the circuit causing sparking problems?
- Do you really want to monitor the switch (which implies a timeout on the problem), or do you need the hardware to detect a error conditon imediately to stop the machine proceeding in an unsafe state (e.g. with a guard open)?
- Do you want a dual reduntant switching arrangement with monitoring?