someone who knows electronics?

[delemonte]

The only real things you need to be sure of are the voltage (19V in this case, I gather), the polarity (assuming that it is DC power we are talking about), and that the PSU is able to continuously provide sufficient current for the DVR (or any device being powered). How high the PSU's rated current output is doesn't matter as long as it is equal to or greater than the current required by the DVR.
Also, be sure to make sure you're comparing the same 'type' of output power rating... i.e. don't be comparing RMS/continuous figures with a Peak/Max figure

It is unlikely that you would be buying/using an unsuitable type of PSU, but it is worth mentioning that there are various technologies that are used to rectify DC power from your house's AC mains power. Just be sure that the PSU you intend to use is of a suitable type - be it a transformer with bridge rectifiers, a regulating circuit, a filtered switch PSU, etc.



Random FYIs regarding posts above:
Whether or not it would blow/trip the AC Mains fuse/CB would depend entirely on the build of the PSU. A fuse will blow for the same reason that a CB will trip and both components serve the exact same purpose, so whether it blows a fuse or trips a CB is somewhat irrelevant.

Just for the sake of mentioning it, CBs do tend to trip 'easier' than a fuse will blow... i.e. CBs have less 'tolerance' for surges of excess current when compared with a fuse of equivalent power/current rating.

Let us know if you have any troubles

[Snotty]

funny you should mention blowing fuses and cb.
because thats how this all came about, came home one night, and half the house had no power.
checked the meter box and the safety switch had been tripped, flicked her back on, everything come back on fine except for the dvr.

the green led on the power supply no longer lights up so i assume shes dead. and yes, tried another powerpoint, and also everything else plugged into the powerpoint it was plugged into works fine.

[delemonte]

The 'safety switch' being the earth leakage breaker, the circuit breaker, or a combined unit (both)?

Hmmmm... if it's the CB that tripped, it sounds like the OEM PSU failed into a closed circuit and thus tripped the CB. You'd better hope the DVR didn't get any sort of voltage spike as a result and fry. If you're really unlucky, it is also possible that the DVR itself could have failed and thus fried the PSU thus tripping the CB. Just something to keep in mind

If it's the ELB that tripped, you might want to consider taking a good look over your current DVR setup and make sure everything is as it should be. There has to be a leak to earth to trip the ELB, and 19V isn't going to leak to earth any time soon - 240V sure will though!

In any case, does this DVR run 24x7? If so, it would be a good idea to get a PSU that can handle the 2.21A with real ease. The 3.4A replacement you mentioned should be adequate, assuming it is genuinely capable of a continuous 3.4A. Check to see if it gets uber hot during use.

[Kudrow]

Just be careful with this kind of equipment. I have DVR and security equipment and some are very fussy when it comes to what current is being fed into them.

It may immediately destroy the equipment, or cause it to fail at a late date or over time.

[Kudrow]

The 'safety switch' being the earth leakage breaker, the circuit breaker, or a combined unit (both)?

Earth Leakage Circuit Breakers (ELCBs) are usually referred to in newer days as Residual Current Devices (RCDs). These will function as a safety switch only.

A combined unit, that is one that acts as a RCD and your conventional circuit breaker/isolator/fuse is called a Residual Current Circuit Breaker with Overcurrent Protection (RCBO). Sometimes, electricians will still wire a conventional circuit breaker/isolator/fuse before the RCBO to isolate the actual RCBO as well.

They all look very similar (the newer ones), apart from fine writing on the fronts of them.

[Kudrow]

See images.

Left to right, top to bottom.

1. 80 amp circuit breaker only. 2. Old 40A ELCB.
3. 16A RCBO (safety switch and circuit breaker combined). 4. New uninsalled RCBOs.
5. 40A RCD (safety switch only)

[poita]

finally a subject that brady knows something about

[Keep'emRunning]

Just be careful with this kind of equipment. I have DVR and security equipment and some are very fussy when it comes to what current is being fed into them.

It may immediately destroy the equipment, or cause it to fail at a late date or over time.

...you mean voltage.. you can have a million amps on a psu/buss and the device will still only draw it's nominal rated current ..unless it's damaged of course

[delemonte]

...you mean voltage.. you can have a million amps on a psu/buss and the device will still only draw it's nominal rated current ..unless it's damaged of course

+1.. one cannot feed additional current through a device with a definite resistance without increasing the voltage.



Conveniently, there are obvious differences between each safety device when looking at the connectors from the rear.

Thanks for the photos Kudrow - I never cease to be amazed by the amount of effort that you guys put into helping each other out... be it just taking photos, or making a special trip out to Timbuctoo to check something out on someone's behalf.



So... did we find out whether this 'safety switch' was actually a safety switch (ELB, RCD) or just a CB? Or, the real question is 'which switch tripped?'

[Kudrow]

...you mean voltage.. you can have a million amps on a psu/buss and the device will still only draw it's nominal rated current ..unless it's damaged of course

Well this depends with DVR's and alarms as to what you have connected to it. How many cameras you have connected to it or how many accessories on the system that draw power from the same PSU.

But yes, I meant voltage.