Extending the life of my relay?

[thylacine1975]

Simple inrush protection will give you the most relay-protection-per-[currency unit]-spent.

Just put something like this (https://au.element14.com/epcos/b573...4472?in_merch=true&MER=MER-L53-L5IB-PD-ALT-ST) NTC thermistor in series with your switched load and your problems should go away. NTC Thermistor surge protectors work by offering a (relatively) high series resistance with the load on initial switch-on. Continued current flow after switch-on causes them to heat (due to I2R losses in their intrinsic resistance) which causes their resistance to drop (NTC = *negative* temperature coefficient, i.e. *less* resistance with more heat), thereby allowing the load to draw full power after a 'gentler' turn on.

The only thing to beware is that they can get *hot* - beyond 100C - depending on the load current, so don't put them against a plastic case. NTC thermistors come in a myriad of shapes, sizes, ratings and (generally low) costs so hunt around to find one that works best for you.

 

[FvM]

Of course I agree about general usefulness of NTC inrush current limiting. But it's not fool-proof, you can still get high inrush currents with repeated switching.

The other point to consider is this. Inrush current limiters are usually built-in to high inrush current devices, e.g. motor inverters. They become necessary if switching of these devices causes serious voltage dips or even tripping of sensitive circuit breakers. A TV or monitor doesn't belong to this kind of devices. It has some inrush current, e.g. 10 or 20 A for a few milliseconds, but this inrush current level is expected to be safely handled by switches and circuit breakers. In other words, if relay contacts are welded when switching a TV, the relay isn't well suited for power applications.

 

[crutschow]

Then what do you suggest?

Why do you ignore my suggestion to use an inrush limiter device :?: They are relatively inexpensive.