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Old 2nd February 2011, 14:48   #406
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Default Re: Inverter or generator?

Just to suggest alternative option, there are solar powered inverters. Take a look if its feasible for you.
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Old 2nd February 2011, 15:14   #407
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1.This laptop idea is actually quite interesting. If done like the way car-leasing works, then it actually will boost performance and morale.

2.When you say with virtualization, you mean cheap laptops connected to a server which runs all the host applications? Until now, I ran virtualization only for back-office teams, but did not actually check this out for development teams.

5.I do need to check on the high computing power bit for our developer requirements.

7.We are in a brilliant nice house with two floors. Very good ventilation with a nice big terrace. We packed off both our air conditioners into sealed boxes. OutSmart360 Alley Blog to see pictures of the place. After coming off from a closed, glass facaded commercial office, this place is fantastic. I think we'll be looking nice and hard for a very well ventilated place as our next office.

12.I will check on whether thin-client's make sense for our development teams. Our design teams which run adobe suites are not probably good examples for this.

14.How old are you man?! I dont think I even know what this looks like.
2. Depends on the development licensing. If there is a floating license which keeps track of the number of licenses being used at a given time, then all you need is a license manager.

5. Same logic holds here. In fact when we were doing CAD, there was a central license manager on the Server, which managed simultaneous use of licenses.

7. I do not what the dust scene is. But in my experience without AC windows are kept open and dust accumulates inside PC and components do blow. This is rarely the case with laptops.

12. Thin clients come in various guises and you can get pretty powerful ones. For basic development you may not need any fancy, excepting CPU power to run inter active debuggers. For testing you need target machines of various configurations.

14. Don't know about him, but I started on Mainframes and then graduated to Mini Computers, and then micros. I am nearly 60. Just to whet your curiosity, I have worked with Vector CAD Monitors!
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Old 2nd February 2011, 19:06   #408
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Default Re: Inverter or generator?

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Btw, we are a dot net shop. So we dont work on linux.
As a user, I loathe the words "This application needs .Netframework etc etc etc..."


Quote:
That is true. I had not considered the AMC. Since we have an IT admin in-house, we dont need an AMC with an external company.
Absolutely agree with Chipz. Desktop is by far the cheapest and easiest to maintain


Quote:
I will check on whether thin-client's make sense for our development teams. Our design teams which run adobe suites are not probably good examples for this.
Well, the people who used to put terminals on our desks (when I was young ) now do this. I have, as I said, no idea about this interesting new technology. I do know, though, how much easier it is to look after one server than forty desktops.


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How old are you man?! I dont think I even know what this looks like.
Well, I think this must have been 1980-something, when I took on managing the first computerisation of accounts in the company where I was then, because, "well, why not you? the rest of us don't know anything about it either." It was just what we now call a "tower," but it ran Unix, and when they put my first DOS PC in front of me, I said, "boring: it doesn't do anything!" --- but that is another story.

My last employers, by the way, had a huge 3-phase Liebert UPS which took up most of the computer room. It would have powered most of the office. They consistently refused to spend money on maintaining it and replacing batteries, until we bypassed it permanently the day smoke came out of it. Eventually, we paid someone to take it away and reclaimed the office space. Very sad. This was no tin-pot company, either, but a small national branch of a Japanese giant. They just had some funny ideas about spending money.

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Old 11th February 2011, 19:33   #409
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Default Re: Inverter or generator?

Hi Guys,

I am to establish a new cold store in Gurgaon. Need opinion from owners of Mahindra/Kirloskar/Cummins.

What DG set do you recommend. Rating required (on 80% utilization) = 48 kVA.

Thanks!
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Old 23rd April 2011, 19:07   #410
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Default Re: Inverter or generator?

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Originally Posted by NetfreakBombay View Post
Given that his location is Bangalore, AC might not be top priority.

Believe me it is - I once worked in an office in Bangalore where the AC vent bust for a month. The temperature outside would go up to 35C and the temperature inside would top 50C - glasshouse effect and concrete effect along with all the electrical equipment in the building
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Old 23rd April 2011, 19:28   #411
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Default Re: Inverter or generator?

On laptop vs. Desktop - desktop will almost always win on all paarmeters and a desktop+30min UPS still costs less than a laptop.

Laptop beats deskptop if you have to provide one to your employees anyway.

Regarding AMC for laptop - even if you have in-house IT keep in mind that laptops are built to less rigorous standards than desktops and provide far fewer options for future upgrades.


On inverter vs. generator - if you take into account the charge/discharge cycle resilience of battery, efficiency of inverter, the fact that without power factor correction most electronic equipment will eat more amperes than it should (and hence drain battery faster) etc. then with the prices of battery and the fact that copper prices are increasing faster than petroleum prices a diesel (or kerosene) genset makes better sense. In areas where you get piped natural gas, that makes even better sense.
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Old 24th April 2011, 12:18   #412
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Default Re: Inverter or generator?

Quote:
Originally Posted by Sn1p3r View Post
Hi Guys,

I am to establish a new cold store in Gurgaon. Need opinion from owners of Mahindra/Kirloskar/Cummins.

What DG set do you recommend. Rating required (on 80% utilization) = 48 kVA.

Thanks!
Do you need it for full time or for power outages?

I suspect that power would be critical to your need, hence I would suggest go for redundancy, that is instead of one 48 KVA get two 24/30 KVA sets. The Cummins sets are the best but also the most expensive. I do not think that Mahindra manufactures either the Engine or the Alternator, and Kirloskar have collaboration with Cummins.

Do the following home work before buying a Genset

1. Find specific consumption of diesel, that is litres/hour at your load
2. Find the oil consumption, that is litres/100 hour
3. Get the cost of maintenance both parts and labour. Generally the maintenance is every 500 hours
4. Find out where the maintenance personnel are stationed. Prefer the company which has them in Delhi/Gurgaon

These would give you the running costs.

Next get a list of their customers in Gurgaon/Delhi/Noida and visit some of them personally to get a feed back.

Please give a lot of weightage to the maintenance aspect as a well maintained DG Set would last a decade or two, while and indifferent maintenance would start giving major head aches within five years. I am attaching some literature for your perusal
Attached Files
File Type: pdf Fuel_Consumption_Chart.pdf (52.9 KB, 257 views)
File Type: pdf DG_leaflet.pdf (127.4 KB, 238 views)
File Type: pdf Load Sheet1.pdf (62.3 KB, 514 views)
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Old 24th April 2011, 13:46   #413
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Default Re: Inverter or generator?

Quote:
Originally Posted by Aroy View Post
Do you need it for full time or for power outages?
...
@Aroy

can you point me to something that'll be useful for my home? 5KVA to 10KVA is what I'm after (budget constraints :( )
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Old 25th April 2011, 12:00   #414
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Default Re: Inverter or generator?

Quote:
Originally Posted by vina View Post
@Aroy

can you point me to something that'll be useful for my home? 5KVA to 10KVA is what I'm after (budget constraints :( )
Vina, the cost of generators is fairly constant till 20 KVA or so. The reason is

1. The cost of housing (silent generator), AMF (Automatic Mains Fail) Panel and other control circuits is between 1 and 1.5L.
2. The cost of small engines < 15HP is fairly constant
3. The cost of Alternator is proportionate to the KVA, but small alternators are more expensive.

That said, the most cost effective DG Set for domestic use is 3 Phase,14/15 KVA. With full installation and warranty a 15 KVA DG set should be around 4L. The advantages of generator is that the duration of supply is dependent on the quantity of fuel stored and not on batteries. So if you have 2-4 AC then the generator makes sense.

The most effective method is

1. Install 1-2 KVA Inverter with minimum battery backup ~ 15 min. Use this for normal lighting, fridge etc.
2. Install a 14 KVA DG, programmed to start within 5 min of power outage.
3. Use DG yo power every thing including the Inverter.
4. Program DG to stop after 1 min of power returning.

Be sure to approach each vendor and get references which you should check up personally. Other factors discussed in my previous post still hold.

CAUTION : Though they may look attractive initially, do not acquire Petrol or Kerosene Generators. These are low duty high fuel consumption devices, meant mainly for recreation and not heavy duty use. Unlike diesel DG Sets, these will last a few years and then pack up.
Some literature
Attached Files
File Type: pdf Genset_Installation_Recommendation-Jakson.pdf (763.5 KB, 1798 views)
File Type: pdf Product Catalogue- Jakson.pdf (2.03 MB, 5823 views)
File Type: pdf diesel_bro.pdf (768.1 KB, 212 views)

Last edited by Aroy : 25th April 2011 at 12:12.
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Old 25th April 2011, 14:38   #415
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Default Re: Inverter or generator?

Thanks Aroy, just commissioned a 82.5 kva Cummins DG with AMF. The load calculation is double of the actual need so that the DG should run in a range of 50 to 80% efficiency.

Also two DGs are always more expensive than the one bigger one. There are new electronic governors that can be effectively used to modulate the fuel usage. i.e., if I am using 50kva the diesel will not be used as per 82.5 kva. Saving fuel, going green

Cheers!
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Old 25th April 2011, 15:51   #416
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Default Re: Inverter or generator?

Quote:
Originally Posted by Aroy View Post
Vina, the cost of generators is fairly constant till 20 KVA or so. The reason is

1. The cost of housing (silent generator), AMF (Automatic Mains Fail) Panel and other control circuits is between 1 and 1.5L.
2. The cost of small engines < 15HP is fairly constant
3. The cost of Alternator is proportionate to the KVA, but small alternators are more expensive.

That said, the most cost effective DG Set for domestic use is 3 Phase,14/15 KVA. With full installation and warranty a 15 KVA DG set should be around 4L. The advantages of generator is that the duration of supply is dependent on the quantity of fuel stored and not on batteries. So if you have 2-4 AC then the generator makes sense.

The most effective method is

1. Install 1-2 KVA Inverter with minimum battery backup ~ 15 min. Use this for normal lighting, fridge etc.
2. Install a 14 KVA DG, programmed to start within 5 min of power outage.
3. Use DG yo power every thing including the Inverter.
4. Program DG to stop after 1 min of power returning.

Be sure to approach each vendor and get references which you should check up personally. Other factors discussed in my previous post still hold.

CAUTION : Though they may look attractive initially, do not acquire Petrol or Kerosene Generators. These are low duty high fuel consumption devices, meant mainly for recreation and not heavy duty use. Unlike diesel DG Sets, these will last a few years and then pack up.
Some literature

Thanks Aroy

If I had the cash I would go for the larger genset, however, let's just say I'm on a budget and roughly 5kVA more than adequately covers my needs anyway (I already have 1.4kV + 0.6kVA installed inverters with pretty solid battery capacity at home - but Ghaziabad is notorious for very long power cuts and the inverters anyway can not support the AC).

One of the reasons I was looking for DGset is that considering electricity cost, inverter efficiency, and battery replacement costs and inverter turns out to be more expensive than a DGset anyway. However if for small capacities cheaper sets are not available then the maths doesn't work.
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Old 25th April 2011, 17:19   #417
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Default Re: Inverter or generator?

Quote:
Originally Posted by vina View Post
Thanks Aroy

If I had the cash I would go for the larger genset, however, let's just say I'm on a budget and roughly 5kVA more than adequately covers my needs anyway (I already have 1.4kV + 0.6kVA installed inverters with pretty solid battery capacity at home - but Ghaziabad is notorious for very long power cuts and the inverters anyway can not support the AC).

One of the reasons I was looking for DGset is that considering electricity cost, inverter efficiency, and battery replacement costs and inverter turns out to be more expensive than a DGset anyway. However if for small capacities cheaper sets are not available then the maths doesn't work.
One solution is to get a small ~ 1KVA Honda Generator and use it to charge your batteries. Beware that these generators are extremely expensive to run. I would not advise "Local" handle starting Generators. Their 5 KVA rating is indicative and can be as low as 2.5 KVA. Further I was told by the supplier that to start a normal window AC 6-8 KVA rating for these generator is required. Once the AC starts the 6 KVA generators can sustain 2 AC.

You can also team up with your like minded neighbours to get a bigger set and share the costs.
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Old 25th April 2011, 19:24   #418
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Default Re: Inverter or generator?

I would like to share the knowledge I have recently acquired thus my word should not be taken as a final statement.

Any equipment that runs has a Upstart load and thus your DG working on a .8 power factor will and should have alteast twice the rating of your maximum load.

Thus if you plan to operate a 2 ACs of rating 1.5 tons then your motor start load is 3 Tons at any point while both the ACs are operational. So your minimum effective output of the DG set should be twice that is 6 kva. But again because both the ACs will cut (condesor taking a break after say 20 minutes or so) at different time thus you can do with 6kva else rule of the thumb is to have the DG set running at 60% to max 80% of its rating.

I hope this helps.

Another thing to remember: Cummins engine with Stamford alternator is considered the best, governors for DGs less than 100 kva are mechanical components and thus dont let anyone take you for a ride. A bigger DG is always economical in its running rather than smaller ones. Also according to my calculations effective cost of running a DG comes to Rs 12 + maintenance per unit.
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Old 25th April 2011, 19:50   #419
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Default Re: Inverter or generator?

Quote:
Originally Posted by Sn1p3r View Post
I would like to share the knowledge I have recently acquired thus my word should not be taken as a final statement.

Any equipment that runs has a Upstart load and thus your DG working on a .8 power factor will and should have alteast twice the rating of your maximum load.

Thus if you plan to operate a 2 ACs of rating 1.5 tons then your motor start load is 3 Tons at any point while both the ACs are operational. So your minimum effective output of the DG set should be twice that is 6 kva. But again because both the ACs will cut (condesor taking a break after say 20 minutes or so) at different time thus you can do with 6kva else rule of the thumb is to have the DG set running at 60% to max 80% of its rating.

I hope this helps.

Another thing to remember: Cummins engine with Stamford alternator is considered the best, governors for DGs less than 100 kva are mechanical components and thus dont let anyone take you for a ride. A bigger DG is always economical in its running rather than smaller ones. Also according to my calculations effective cost of running a DG comes to Rs 12 + maintenance per unit.

Thanks for the computation. However inverter based power is not really cheaper (in UP at least):

Tariff is close to Rs. 4/- per unit, with losses of charging and discharging on an average inverter (assuming 80% efficiency both ways) you get overall charge of almost Rs. 6.50/-per unit.

Add to this the fact that batteries usually last no more than 500 full charge-discharge cycles (this is still more than 2 years of use - most batteries are bad in less than that) and battery costs and you'll find that inverters are much more expensive than generator - except that inverters are available in smaller capacities and also a good amount of expense is front-loaded (in terms of price of generator) for the generator set - so inverters are more popular.

Pollution, space and noise are other factors of course.
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Old 25th April 2011, 19:53   #420
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Originally Posted by Aroy View Post
One solution is to get a small ~ 1KVA Honda Generator and use it to charge your batteries. Beware that these generators are extremely expensive to run. I would not advise "Local" handle starting Generators. Their 5 KVA rating is indicative and can be as low as 2.5 KVA. Further I was told by the supplier that to start a normal window AC 6-8 KVA rating for these generator is required. Once the AC starts the 6 KVA generators can sustain 2 AC.

You can also team up with your like minded neighbours to get a bigger set and share the costs.
I'm not even considering the "local" crap - it has no reliability whatsoever.

Neighbours are, well, neighbours. Some do not even pay for the community watchmen - who will pay for fuel and other expenses?
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