House mains supply interuptus.

For what I know, power downs don't damage your equipement.

Lightning does.

quote:

Can anyone tell me if these many occurrences do damage?

It shouldn't do - it'll just make nasty noises as its not a sequenced power up (preamp on first etc).

James

I wonder if MK or someone does a crowbar circuit breaker that switches off when the power goes off, and stays off when the power comes on?

Jon

An “active RCD” socket or adaptor will do the job.

Except it would be putting an RCD over the mains, which I dont want. I want a very high resistance (pure resistance) probe which tells me whether there is voltage there, and then releases the crowbar when not. I'm trying to avoid putting nasty power supplies, diodes etc etc across the mains, keeping it as pure as possible -- or "hungaroring quality" as PaulS described my setup :-)

Guess I'm lucky in these Norwich suburbs, where I rarely have a failure (every 3 or more years?), but then I have underground cables which are far less susceptible that overhead lines.

However, it is a pain, and a worry, when this happens, though I didn't know that my RCD would trip in the event of a power failure, which gives some comfort.

I am surprised, therefore, that you (JOHN HONEYBALL) avoid RCDs. Mine are part and parcel of 32 amp. RCBOs, which I thought provided adequate mains continuity allied to lower resistance but with the safety aspect (RCD) having no drawbacks.

Do you know something I don't?

Sure I have them, but I dont want to be adding more active components, if you see what i mean.

Every once in a while my tuner will just go off and my computer shuts down, but when I go over the system lights are still on. When I power up the tuner it has reset itself to the first station. Of course I also have to restart the computer. My landlords in this late 40s apartment still have the old fuse boxes with the round screw in types. Why they don't change to the modern boxes I don't know. Just cheap I'd guess.

quote:

Originally posted by Pussycat:
I didn't know that my RCD would trip in the event of a power failure, which gives some comfort.

It might not.

The RCD in my consumer unit doesn’t trip on mains power failure.

Active RCD’s trip, passive RCD’s don’t.

I'm on a learning curve here. I've solicited enlightenment from a Physics lecturer friend and an electrician.

Neither has heard of an ACTIVE RCD.

I'd appreciate you (FATCAT) or Jon Honeyball, or in fact anyone, to say what this is and how it differs from the standard residual current device.

Thanks in anticipation.

Pussycat

I’m surprised your electrician friend is in the dark, although your average domestic electrician probably wouldn’t have come across or know of the existence of an active RCD.

What you describe as a standard RCD is probably a passive RCD.


http://en.wikipedia.org/wiki/Talk:Residual-current_devi...CDs_actually_trip.3F


How do RCDs actually trip?
Using the example of the illustrated "outlet-style" RCD, the description used to speak about the solenoid being continuously energized and that providing the latch that kept the RCD "reset". This description is clearly inconsistent with at least US-style RCDs as it would imply that a power failure would also lead to the dropping-out of all of the RCD solenoids, their subsequent tripping, and the need to manually reset all the RCDs after power was restored. This ain't the way it works in practice.
I conclude from this that the mechanism operates in the opposite fashion: The latch is mechanically held and the RCD activates the solenoid when it wants to "trip" the RCD by unlatching the latch. I've changed the text to reflect this view of the world. But if Europe has "outlet-style" RCDS and they operate as originally described, please feel free to extend the text to explain this.
Meanwhile, I guess I'll take an American RCD apart this week-end and check for certain. :-)
Atlant 19:27, 3 Jun 2005 (UTC)
In Europe you can get both passive rcds (which don't trip out on power failure) and active rcds (which do). Generally most rcds in consumer units etc are the passive type but the active type is considered advisible for supplying equipment which can pose a danger on unexpected re-energistation. Plugwash 20:57, 3 Jun 2005 (UTC)

Pussycat

A better explanation.

http://en.wikipedia.org/wiki/Residual-current_device

Many thanks, FATCAT, for your helpful info. on active RCDs.

I have a feeling you're not in the U.K., and also that active RCDs are rerely used in this country; possibly because of different mains supplies/installations.

By the way, my wife was tickled pink by the feline emphasis, preceded by a canine (Wolf2)

quote:

Originally posted by james n:

quote:

Can anyone tell me if these many occurrences do damage?

It shouldn't do - it'll just make nasty noises as its not a sequenced power up (preamp on first etc).

James

Not for this forums EQ. The preamps mute on power up and mute long before the voltage is low enough to make noise. Low voltage is a non issue as are moderate spikes. Lightning is about the only danger and I'm with Jon's view on protection. Not what I'd do.