Oversized UPS

Determine the manufacturer of the UPS. The vendors just sell them. Compare the manufacturers before you decide,

UPS's have a high markup, so the vendor may really be sacrificing profit for the future potential of sales.

Have the vendor itemize his cost for each item in the project, including profit margin.

Their cost should be very close to each other.

Do this for all vendors and you will get a good idea of who is really giving the best deal.

Here is a link on industrial UPS manufacturers to get you started:

https://www.mingchele.com/blog/ups/top-10-industrial-ups-manufacturers-in-usa/

RE: Breaking out prices in an itemized estimate vs. lump sum price offer

I have had a few customers ask or demand to know my line item costs of materials, transit, labor, taxes, overhead, profit… I told them to pound sand. This is my business to operate, I would reveal no internal information to anyone. Period.

Aside from the 20% increase in apparent power, is the proposed equipment in line with your other specifications?

All of them?

Actually the spec calls for 110% overloading of 1 hour; since they could not comply to this, hence offering 180kVA UPS which covers for the 110% overloading

Your specification sounds like waffle engineering. I’ve seen overload specs on generators, they are somewhat common, also waffle engineering. Decide what you want and ask for it. The 180kVA unit will be just fine. The distribution equipment will be sized properly for your “1 hour” overload and will operate just as anyone else in the world will expect, without extraneous emergency events.

Spec calls for 2 hours and 6 minutes.

Our anonymous original poster has so advised, this in response to a request for some detail; how could it be any clearer?

This thread seems to be yet another poster child supporting the sentiment of ‘I don’t comment on Anonymous Poster threads’.

Continued from #9

… Which is kind of sad. I was hoping to find out what we are discussing that warrants a UPS of 150kVA and maybe a little extra… another ten percent or so… I guess.

110% overloading for 1 hour - These are intended for sizing the semi-conductors. As you know, semi-conductors have a very limited thermal capacity and they are size for current and not for power. What we want with this is to have a bit over overcapacity in the design such that we can extend the installation during its life time and especially to have sufficient margin in the design to sustain short circuit currents.

If you also size the copper and iron to take this overload, it could be cheaper to operate.

It’s unlikely for a unit this size for someone to re-do their heat calculations for the various components, so a standard design would be your economic and conservative choice.

If they were building it from scratch, then a specification like that would make sense.

As the selection basis for your decision, you may need to evaluate the electronics circuit as the key design criteria.. application and usages of electronic power components, basing on their type and rated specifications..

The immediate availability of the any needed electronics replacement and associated repair costs in case the need arise.. since the copper and mechanical sections are standard and negligible..

I mean if I was in the management, I will go 180kVA with the same price of 150kVA or better lower. Why stress the system with overloading in the first place? I don't like the word overloading I guess. It is because in design that overloading belongs to the critical region of fatigue or failure and who knows, that band gap of critical region near off or far off breakdown. Load in reality is very far from the books and it aint always academics(theoretical).

Think of this, 125% of 150kVA is 187kVA and 125% of 180kVA is 225kVA. Now would it rather make or break?

What say you?

What was the originally planned unit, just a circuit breaker panel? We don't even know if you need uninterrupted power for any part of this unspecified installation.

The complete UPS unit (double conversion, bypass, static switches, maintenance switches) along with batteries. As a part of UPS, it would have one outgoing circuit breaker to protect the outgoing cable. The UPS distribution panel is not part of the UPS

Just some simple stuff probably:

1. Can my existing DB supply the inrush current (if present) and full load of battery charging, or will it trip my circuit breakers feeding the UPS by virtue of being 20% larger? If so, is it easy/practical to just increase the rating of the CB for this circuit in the DB? Additional costs?
2. Does the existing space allow for this larger unit (enclosure modification costs), can I reach the batteries easily, etc. (Maintenance / labour costs)
3. Any increased ventilation/cooling issues? (Doubt it, but modification costs may then apply.)
4. Non-price items, when compared to your usual suppliers:
1. Is the warranty the same (warranty period, warranty conditions, on-site vs off-site assistance, reaction & replacement times, etc.)
2. Maintenance requirements
3. Spares cost & availability
4. Built-in surge protection specs on both the incoming and outgoing sides
5. Will the batteries supplied give you the correct time duration of backup at the specified load (be that 100% or 110%)? Suggest that you test that for a new supplier.

In my experience power required will increase as long as there are users. Excess capacity ensures longevity of the system.

If the UPS supplier has a solid reputation and a good warranty I would seriously consider it. Compare pricing based on $/kVA and see if the price is competitive.

If value for money and the budget allows, buy the bigger unit. The only long term issue would be the cost of replacement. However, having the bigger unit will reduce the need for early replacement or upgrade when the user demand growths beyond the current plan.

I've been out of the scene for about ten years, but here's what I'd think:

1. Is my electrical system able to accommodate the higher electrical demand of the new UPS? This includes breakers and wires at the site where the UPS is located, and the substation.
2. Does the new UPS fit into the space where it will be located?
3. Some suppliers remove certain features or services to be able to offer the lower price. Is the warranty a partial warranty? Is it shorter? What about after sales service? Is the new UPS using cheaper batteries?

I can't think of any more, but others might be able to give their own possible issues.

regards,

Vulcan