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Microsoft Word - Energy Savings Opportunities in Continuous Running Applications White Paper ROMAN MANUFACTURING INC.
Energy Savings 
Opportunities in 
Continuous Running 
Applications 
White Paper 
 
Stanley F. Rutkowski III 
Mark B. Siehling 
Robert S. Hofman 
Donald B. DeCorte 
9/19/2008 


RoMan Manufacturing Inc.
Page 2 of 9

Energy Savings Opportunities in Continuous Running Applications

With the rising costs of electrical energy in the global marketplace, manufacturing
industries are investigating the opportunity to reduce costs in their processing. During
the times of low cost energy, little or no influence was given to electrical losses in a
system as it had minimal impact on the operating cost of manufacturing a product. As
the cost of electricity has risen, the impact of the operating cost has come to the forefront
as an issue of competitiveness.

The cost of electricity is typically focused on five aspects of power:

1)

Real Power (kW)
2)

Power Factor
3)

Peak Demand
4)

Reactive Power (kVAR)
5)

Total Power (kVA)



The easiest and single largest of the five aspects to put a monetary value to is the Real
Power savings. A electric utility bill typically shows this cost in a set price in kilowatt
hour (kWH). The other four aspects of the power are dependant on other factors in a
facility, so this report will only focus on dollar savings (in $US) for the Real Power
Savings.

In many industrial processing applications such as resistance heating, physically large air
cooled transformer systems are installed. Systems incorporating air cooled transformers
need to be kept in a stable temperature range and protected from dust or debris which
could reduce heat dissipation. With this isolation, large and material intensive copper
secondary circuits needed to be designed to accommodate the air cooled transformers.

With the use of a sealed water cooled transformer system, the limitations of the air cooled
system are removed. The ambient temperature for the transformer now becomes the
temperature of the inlet water. Also with any epoxy encapsulated transformer the
vulnerability to contamination from dust or debris is removed. Typically other
components in the electrical or mechanical system are already water cooled, so the
impact of the water to the cooling system of the transformer is minimal. With the closer
proximity of the transformer to the work piece, more electrically efficient and less
material intensive secondary circuits can be employed in the system. RoMan Manufacturing Inc.
Page 3 of 9


RoMan Manufacturing Incorporated has participated in eight case studies showing the
electrical benefits of the water cooled transformer system. These studies were conducted
on three continents with varying primary voltages and frequencies.

Case Studies #1 and #2

Position Air
Cooled
System #1
Water Cooled
System #1
Air Cooled
System #2
Water Cooled
System #2
Primary
Current
140.21 A
50.5 A
128.42 A
49.0 A
Secondary
Current
4,767 A
4,048 A
4,366 A
3,980 A
Reduction in
Primary
Current
89.71
A 79.42
A
Power
Factor
0.47 0.65 0.50 0.67
Real Power
21.0 kW
12.5 kW
22.2 kW
12.0 kW
Cost of kW per
Year
$10,117.80 $6,022.50 $10,695.96 $5,781.60
Savings in Real
Power per
Year*
$4,095.30 $4,914.36
Reactive Power
23.7 kVAR
6.7 kVAR
22.2 kVAR
5.9 kVAR
Total Power
31.7 kVA
14.2 kVA
31.4 kVA
13.4 kVA
* Price of kWH is $0.055 USD

In System #1
1)

The Real Power is 59.5% of the existing application (12.5 / 21.0 X 100%). With
the cost of $0.055 per kWH the savings would be $4,095.30 per year.
2)

The Power Factor of the system will be increased by 38.3% ((0.65-0.47) / 0.47 x
100%).
3)

The Peak Demand Current is 36.0% of the existing application (50.5 / 140.21 x
100%).
4)

The Reactive Power is 28.3% of the existing application (6.7 / 23.7 x 100%).
5)

The Total Power is 44.8% of the existing application (14.2 / 31.7 x 100%).
In System #2
1)

The Real Power is 54.1% of the existing application (12.0 / 22.2 X 100%). With
the cost of $0.055 per kWH the savings would be $4,914.36 per year. RoMan Manufacturing Inc.
Page 4 of 9

2)

The Power Factor of the station is increased by 34.0% ((0.67-0.50) / 0.50 x
100%).
3)

The Peak Demand Current is 38.2% of the existing application (49.0 / 128.42 x
100%).
4)

The Reactive Power is 26.6% of the existing application (5.9 / 22.2 x 100%).
5)

The Total Power is 42.7% of the existing application (13.4 / 31.4 x 100%).
The installed base for each of the two systems is 200 units. With a total conversion to the
water cooled system in the facility the power saving per year in Real Power alone would
be $1,801,932.00 (200 x $4095.30 + 200 x $4914.36).


Case Study #3

Position Air
Cooled
System
Water Cooled
System
Primary Current
106.4 A
92.6 A
Secondary Current
5,000 A
5,000 A
Reduction in Primary Current

13.8 A
Power Factor
0.79
0.89
Real Power
40.3 kW
39.5 kW
Cost of kW per Year
$35,302.80
$34,602.00
Savings in Real Power per Year*1

$700.80
Reactive Power
10.7 kVAR
4.9 kVAR
Total Power
41.7 kVA
39.8 kVA
*1 Price of kWH is $0.10 USD

1)

The Real Power is 98.0% of the existing application (39.5 / 40.3 X 100%). With
the cost of $0.10 per kWH the savings would be $700.80 per year.
2)

The Power Factor of the station is increased by 12.7% ((0.89-0.79) / 0.79 x
100%).
3)

The Peak Demand Current is 87.0% of the existing application (92.6 / 106.4 x
100%).
4)

The Reactive Power is 45.8% of the existing application (4.9 / 10.7 x 100%).
5)

The Total Power is 95.4% of the existing application (39.8 / 41.7 x 100%). RoMan Manufacturing Inc.
Page 5 of 9

The installed base for each of the two systems is 62 units. With a total conversion to the
water cooled system in the facility the power saving per year in Real Power alone would
be $43,449.60 (62 x $700.80).

Case Study #4

Position Air
Cooled
System
Water Cooled
System
Primary Current
90.0 A
84.0 A
Secondary Current
4,950 A
4,947 A
Reduction in Primary Current

6.0 A
Power Factor
0.86
0.92
Real Power
29.4 kW
29.4 kW
Cost of kW per Year
$15,452.64
$15,452.64
Savings in Real Power per Year*2

$0.00
Reactive Power
4.8 kVAR
2.6 kVAR
Total Power
29.8 kVA
29.5 kVA
*2 Price of kWH is $0.06 USD

1)

The Real Power is 100.0% of the existing application (29.4 / 29.4 X 100%). With
the cost of $0.06 per kWH the savings would be $0.00 per year.
2)

The Power Factor of the station is increased by 7.0% ((0.92-0.86) / 0.86 x 100%).
3)

The Peak Demand Current is 87.0% of the existing application (84.0 / 90.0 x
100%).
4)

The Reactive Power is 93.3% of the existing application (4.9 / 10.7 x 100%).
5)

The Total Power is 99.0% of the existing application (29.5 / 29.8 x 100%).
The installed base for each of the two systems is 74 units. With a total conversion to the
water cooled system in the facility the power saving per year in Real Power alone would
be $0.00. In this application, the increase of the power factor attributed more of the total
power to the real power in the application, resulting in no dollar savings in kWH while
showing savings in the other aspects of the system. Each application needs to be assessed
for its savings potential as not all applications allow for savings in power.


RoMan Manufacturing Inc.
Page 6 of 9

Case Study #5

Position Air
Cooled
System
Water Cooled
System
Primary Current
85.1 A
73.3 A
Secondary Current
5,280 A
5,280 A
Reduction in Primary Current

11.8 A
Power Factor
0.75
0.84
Real Power
23.0 kW
22.1 kW
Cost of kW per Year
$11,081.40
$10,647.78
Savings in Real Power per Year*3

$433.62
Reactive Power
7.7 kVAR
4.2 kVAR
Total Power
24.3 kVA
22.5 kVA
*3 Price of kWH is $0.055 USD

1)

The Real Power is 96.1% of the existing application (22.1 / 23.0 X 100%). With
the cost of $0.055 per kWH the savings would be $433.62 per year.
2)

The Power Factor of the station is increased by 12.0% ((0.84-0.75) / 0.75 x
100%).
3)

The Peak Demand Current is 86.1% of the existing application (73.3 / 85.1 x
100%).
4)

The Reactive Power is 54.5% of the existing application (4.2 / 7.7 x 100%).
5)

The Total Power is 92.6% of the existing application (22.5 / 24.3 x 100%).
The installed base for each of t