Date post: | 16-Jul-2015 |
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TCO of transformers
Minute Lectures
What is the TCO of a transformer?
The Total Cost of Ownership, from purchase to decommissioning
Also called the Life Cycle Cost (LCC)
Goal: to compare transformers on
an equal basis in order to make a
purchasing decision
TCO of transformers
Minute Lectures
What are the components of the TCO?
TCO = Purchase price+ installation cost+ value of energy losses+ maintenance and repair cost+ decommissioning cost
TCO of transformers
Minute Lectures
Do all components have to be calculated? (1/2)
The TCO is not used for budgeting purposes, but to accurately compare transformers when purchasing
Therefore, only the components that differ from one transformer to another need to be calculated
TCO of transformers
Minute Lectures
Only those that differ from one transformer to another:
• Purchase price
• Lifetime value of energy losses
• Installation, maintenance and decommissioning cost: only when different technologies are compared (e.g. air-cooled vs. oil-cooled transformers)
Do all components have to be calculated? (2/2)
TCO of transformers
Minute Lectures
Value of energy losses
TCO = purchase cost + TCCloss (total capitalized cost of losses)
TCCloss = A * no load loss + B * load loss
A: easiest to be read off graph
B = A * (Loading)2
Loading = the expected average load over the life span of a transformer, harmonics incorporated.
TCO of transformers
Minute Lectures
The A-factor (1/2): graph
At an electricity price of 100 €/MWh
0,00
2,00
4,00
6,00
8,00
10,00
12,00
14,00
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20Years
A f
ac
tor
(eu
ro/W
) a
t a
n e
lec
tric
ityp
ric
e
= 1
00
Eu
ro/M
Wh
6,75
3% 4% 5% 6% 7% 8% 9% 10% 11% 12%Interest
TCO of transformers
Minute Lectures
The A-factor (2/2): example
Example: what is the A-factor if the interest rate is 5%, the economic life span of the transformer is 10 years, and the electricity price 80€/MWh?
Answer: € 6.75 (see graph) * 80/100 = € 5.40
TCO of transformers
Minute Lectures
Example (1/3): conditions
Comparing a standard 1600 KVA transformer with a high efficiency unit
Characteristics:
Conditions:• Average loading: 65%, 24 hours a day, 7 days a week
• Average electricity price: 40 €/MWh• Average interest rate: 7%• Economic lifetime of the transformer: 20 years
1600 kVA transformer Pn (W) Pk (W) Purchase price (€)Existing 2800 15207 14451Energy efficient 2670 14218 14990
TCO of transformers
Minute Lectures
Example (2/3): A-factor
Total LCC = Purchase Price + A * no load loss + B * load loss
A = 9.35 €/W (see graph) * 40/100 = 3.74
B = A * (0.65)2 = 1.58
TCO of transformers
Minute Lectures
Example (3/3): conclusion
Standard transformer: Ct = 14,451 + 3.74 * 2,800 + 1.58 * 15,207 = €48,950
Energy Efficient: Ct = 14,990 + 3.74 * 2,670 + 1.58 * 14,218 = €47,440
(Pay-back period: about 5 years)
TCO of transformers
Minute Lectures
General conclusion
Energy losses can have a significant impact on the TCO of transformers, since they have a very long lifetime
The difference between the purchase price of a standard transformer and an energy-efficient one is paid back several times over the transformer’s lifespan
TCO of transformers
Minute Lectures
Round-up
TCO of a transformer is typically more than 3 times its initial purchase price
When choosing among transformers, make sure to base comparisons on TCO
In most cases, purchase price and value of energy losses are the main components in the TCO
It is prudent to purchase a more expensive, high-efficiency transformer, because it often yields a lower TCO
TCO of transformers
Minute Lectures
Links and references
• Case studies – industrial transformers>>
• Spreadsheet tool for life-cycle evaluation>>
• K-Factor & Factor K calculation>>
• Leonardo ENERGY resources on transformers>>