Will Step down transformer affect HiFi's performance??

I am surprised that an inverter blew up anything. An inverter, since it provides power stored and transformed from a battery should provide the cleanest power possible. There should be no spikes, and no fluctuation. Only thing is at the end, when the batteries are dying out, you will have a continuous drop in voltage till the system dies.

Can you use an AVR with an inverter? I would say no unless you have an inverter that can take a huge load. If you read the specifications of the inverter, it will be mentioned what kind of load it can take. Most residential inverters are made to keep a couple of fans, and a couple of tube lights burning till the mains power come back. Remember amplifiers and AVR consume huge loads, particularly when they are playing at high volumes. A combination of an AVR, a DVD Player, and a TV will drain your inverter quite quickly.

The best combination is to run your AVR through a stabilizer, and a power conditioning unit such as line filter, and run the system only when you have mains power.

I go by the Amp's fuse rating.

Most (or all) amps are provided with Slow Blow type fuse (those are indicated by letter 'T' [Time] associated with its current and voltage rating) .

Why 'Slow blow' ? As I mentioned above amps take higher current at cold start (that is when you swict on the amp ) as well as during delivering complex music sections, while normal steady state current is much lower.

If a fuse is fitted in accordance with the steady state current , it will blow during start up and dynamic deliveries, while fuse rated as per the In rush current won't protect the amp when it operates at steady state current (most of the time. )

Slow blow fuse can take a momentary excess current load than its rated current this helps to tide over in rush current demand , hence the fuse won't blow while under normal conditions if the amp tries to draw excessive current over a longer period the fuse blows and protect the amp.

Slow blow fuse can withstand 2-3 times normal rating that is printed on the fuse. So take this steady state current fuse rating and mutiply by 3 to arrive at worst case current drawn by the amp. Then multiply it by 230 to get KVA rating. Then multiply it by 1.2 to comensate for power factor, assuming that amp's input transformer is having 0.8 lagging pf. This will give you a correct estimate of actual KVA requirements , agian multiply it by 1.3 to have some safty buffer. Now you know what KVA stab to order!

Here I am considering only Amp, if you have any other current hungry equipments also to be powered then add respective VA requirements.



My amp takes 0.8 A under steady state and probably 3 A worst case, I have provided a 3 KVA Krykard servo voltage stabilizer which can supply around 13 Amp.




Hope this helps.


SUhas

Hi Venkat
Thanks for your insightful posts on the forum.
Even I was surprised at this. I have microtek 800Va inverter coupled to a 190Ah battery and I get good backup even with 29 inch CRT on for most of the time for last 3 years without any issues. It also manages to run a semi auto washing machine and mixer!

Things changed when i bought a cooler last year and when there was a power cut, the cooler started making strange noises. I immediately switched it off and it saved the cooler. But the next time in my absence, it just blew up. The cooler had problem working on square wave I guess.

Other incidence was when I was running my 2.1 speakers though a spike guard and there was a power cut. I guess it was too much to handle for the inverter with whatever was happening in the spike guard and it started beeping abruptly. After a while the spike guard gave off. I didnt realize it were the speakers that were causing the problem.


Now the inverter is always switched off so that in case of power cut I have sufficient time to switch off these sensitive things before I switch it on.

Hence, every time I have to buy a piece of electrical equipment I have this question - whether it will work on inverter!!

Suhas:

We are both talking about the same thing. You can calculate the load from either amperage or from wattage, but both will arrive at the same volt amps. This is assuming that the load factor is the same.

As you mentioned, you can also calculate the load by multiplying the amperage with the voltage - either 110 or 230. Assuming the load factor is the same, you will arrive at the same results. In other words, amp*v/LF and W/LF will be the same.

Couple of things about your calculations:

1. If I am not wrong, a fuse will be rated not at steady state, but to withstand max load. In addition, the system at full load will be only 75 to 80% of the fuses's rated capacity. If this is not done, you will be changing the fuse everyday. Thus. the fuse itself has a good buffer. In addition, if it is a slow blow fuse, it is further capable of withstanding (as you said) 2 to 3 times it normal rated capacity during a in-rush.

2. In-rush and the need for a slow blow fuse is usually meant for lighting elements and motors where there is an inertia that has to be compensated for.

3. In a solid state electronics such as amp, the initial load when you switch on the system is only the quantum of energy needed to fill the capacitor and the time taken to do that. This quantum of energy should not strain the system beyond 150% of its normal load, and the time taken should be less than 10 seconds.

Though there is no harm, I do believe you are being overly cautious in calculating the load for the stabiliser. Actually providing for just the right capacity at the stabiliser end may be more prudent, as the stabiliser will trip or shut down in the event of a overload, thus protecting the expensive audio equipment.

Other than the fact that, in addition to the load factor, you are adding for a buffer at the fuse level, we are both talking about the same thing.

venkat, suhas....just out of curiosity (and a lot of gratitude)....what do you guys do for a living? i am seriously regretting dropping science after 10th standard....of course...if i'd taken science i would have regretted dropping humanities (and wouldn' have ended up being a lawyer probably).....so you can't really win

Well, I am an Post Graduate in Economics, and I manage software companies. I have been in the software business for about 25 years.

Cheers

FYI, Bryston now markets the Torus power range of power conditioners and hence now no longer recommends against using one. Maybe they realised that their "high-quality, dedicated circuitry in the power supplies to reject RF, line spikes and other power-line problems" is not good enough???

Bryston Limited - Music For A Generation
Torus Power Audio/Video Power Conditioners with Isolation and Surge Suppression - Clean Power

I am a post graduate in Electrical Engineering. I am in the domain of Control Systems Engg, Process Instrumentation and worked with several companies in India and abroadf for past 22 odd years . At present working as a Consultant to Indian's number one IT company.

I also have got 4 years of training in Indian Classical Music (both Vocal and Instrumental) under the guidance of Pt Arvind Gajendragadkar. I listen to Jazz, Indian Classical , Western Classical and regional folk music.

Apart form music my other interests are Photography, architecture and reading.

You are very correct awedeophile. They are marketing Torus power conditioners and most recent reviews of bryston gear are all done using Torus power conditioning.
In spite of all this i was surprised to find the same old '' connect our amplifiers directly to the wall outlet " in the manual of the 4 B amplifier i received last month.
Dont really know what to make of it.
Regards

I suggest disbelievers try this : take your TV (should be 29inches or bigger any size, and fed with a dvd video or clear high quality cable signal). Just add a power conditioner or power line filter of good quality. The picture difference is significant even if you have a clean/modern home power wiring in Mumbai or any big city. I suggest this because its easier to see the difference than hear it. Power cords supplied with modern TVs are good enough and replacing them wont change things.

The same way, you will be able to hear the improvement in sound only if you have a system costing over 10 lacs in my opinion, or else you have problems with noise and voltage in your existing inputs that need a conditioner/isolator+filter. But these things do make an audible difference, you have to try them to see if they help your situation or not.