Turn down the heat: Pacific Steel Casting Co. has seen energy cost reductions in three of its plant's electric arc furnaces with the use of a demand meter.The modern electric arc furnace An electric arc furnace (EAF) is a furnace that heats charged material by means of an electric arc. Arc furnaces range in size from small units of approximately one ton capacity (used in foundries for producing cast iron products) up to about 400 ton units used for secondary (EAF EAF - Effort Adjustment Factor ) combines four major technologies: high power electrical generation and transmission, advanced electrical and mechanical furnace furnace, enclosed space for the burning of fuel. There are many kinds of furnaces, the type depending upon the fuel and the use to which the heat produced within it is put. Most familiar are the furnaces used in the heating of buildings. design, high performance manufactured-graphite electrodes Electrodes Tiny wires in adhesive pads that are applied to the body for ECG measurement. Mentioned in: Electrocardiography and improved refractories. The greatest advantage of the EAF is the flexibility it brings to the steelmaking Steelmaking is the second step in producing steel from iron ore. In this stage, impurities such as sulfur, phosphorus, and excess carbon are removed from the raw iron, and alloying elements such as manganese, nickel, chromium and vanadium are added to produce the exact steel process, producing different batches of metal with altered final properties. However, the EAF also has a great disadvantage--it requires a large amount of energy for operation. By limiting its EAF's highest power demand during any given interval interval, in music, the difference in pitch between two tones. Intervals may be measured acoustically in terms of their vibration numbers. They are more generally named according to the number of steps they contain in the diatonic scale of the piano; e.g. with the use of a device (readily available from a variety of sources) called a demand meter meter, unit of measure meter, abbr. m, fundamental unit of length in the metric system. The meter was originally defined as 1/10,000,000 of the distance between the equator and either pole; however, the original survey was inaccurate and the meter was later (DM) Pacific Steel Casting Steel casting is a manufacturing process in which molten metal is poured into a mold, allowed to solidify within the mold, and then the mold is broken and the solid piece is taken out. Co., Berkeley Berkeley (bûr`klē), city (1990 pop. 102,724), Alameda co., W Calif., on the E shore of San Francisco Bay just N of Oakland; inc. 1878. Originally (1820) part of a Spanish rancho, the site was purchased by Americans in 1853. , Calif., has curbed curb n. 1. A concrete border or row of joined stones forming part of a gutter along the edge of a street. 2. An enclosing framework, such as that around a skylight. 3. the high costs associated with operating the expensive furnaces at three of its metalcasting plants. What is Power Demand? Power demand is a charge that reflects the highest energy usage rate by a piece of equipment recorded in any measurement interval. A fixed, half-hour measurement interval is most common. The monthly demand charge is based on the greatest power demand recorded during a measurement interval. The power company's electric utility system must be scaled to deliver not just average demand loads but peak demand loads. For example, an electric motor requires more current to start than when at operating speed The operating speed of a road is the speed at which motor vehicles generally operate on that road. The precise definition of "operating speed", however, is open to debate. , thus creating a spike A burst of extra voltage in a power line that lasts only a few nanoseconds. See power surge, power swell, sag and surge suppression. (jargon) spike - To defeat a selection mechanism by introducing a (sometimes temporary) device that forces a specific result. in power demand. Because of this peak demand on your utility company's electrical system, it makes large investments in auxiliary auxiliary In grammar, a verb that is subordinate to the main lexical verb in a clause. Auxiliaries can convey distinctions of tense, aspect, mood, person, and number. generation and distribution equipment. This auxiliary equipment Noun 1. auxiliary equipment - electronic equipment not in direct communication (or under the control of) the central processing unit off-line equipment buffers capacity, making the electric company capable of producing the highest power demand that you might require during any given interval. The incurred investment costs Those program costs required beyond the development phase to introduce into operational use a new capability; to procure initial, additional, or replacement equipment for operational forces; or to provide for major modifications of an existing capability. are passed to customers in the form of peak demand surcharges. The energy demand of most industrial and commercial facilities is typically very uneven over an extended period of time. The result is peak demand charge that represents a large fraction (usually 30-40%) of the total power bill. Because demand loads roughly follow a curve throughout the day, utility companies define periods of time when the cost of power demand increases. Demand loads reach their maximum in the summer months (May 1 to October October: see month. 31), and power companies, such as the one providing energy to the three plants studied here, divide the days during that service time into categories--peak, partial-peak and off-peak off-peak adj. Not in the period of most frequent or heaviest use: lower rates for telephone calls made during off-peak hours; travelers who take advantage of off-peak fares. . Winter demand months are from November November: see month. 1 to April 30 and are divided into partial-peak and off-peak hours. Minimizing Power Demand with the Demand Meter The DM can limit power demand in two ways. Power demand control (PDC (1) (Primary Domain Controller) A Windows NT/2000 service that manages security for its local domain. Every domain has one PDC, which contains a database of usernames, passwords and permissions. ) manages consumption with preset preset Cardiac pacing A parameter of a pacemaker that is programmed permanently when manufactured limits, which in itself can lead to significant cost savings. The DM has the ability to control up to eight electrical power loads or objects. Examples of such power loads are compressors, lighting and furnaces. Any device consuming electrical power, which can be temporarily power-reduced or turned off, is a power load. When the DM disconnects all or part of a load via the PDC, the object is said to be power reduced. Although the DM provides this kind of set power reduction, it also includes a clock function, which controls power demand within a rate schedule. In normal operation, power consumption is measured continuously, and if consumption exceeds a preset control limit, the object is power reduced to limit the power demand. The clock function provides the ability to power reduce the EAF during predefined intervals, for example, "summer peak hours peak hours npl, peak period n → horas fpl punta peak hours peak npl → heures fpl d'affluence or de pointe between 1200 hours and 1800 hours." The PDC and the clock function also can be invoked simultaneously si·mul·ta·ne·ous adj. 1. Happening, existing, or done at the same time. See Synonyms at contemporary. 2. Mathematics . If a reduction is required for the EAF to stay within a designed control limit, then the object may be power reduced by the PDC function even though the clock function might indicate the object should be in operation. On the other hand, a power reduction scheduled by the clock function will be invoked even though it may not be required on the basis of the PDC. Demand Lower Rates Pacific Steel fitted three plants with DMs and analyzed an·a·lyze tr.v. an·a·lyzed, an·a·lyz·ing, an·a·lyz·es 1. To examine methodically by separating into parts and studying their interrelations. 2. Chemistry To make a chemical analysis of. 3. their performance for cost reduction. Because of differences in the individual furnaces, each DM was configured con·fig·ure tr.v. con·fig·ured, con·fig·ur·ing, con·fig·ures To design, arrange, set up, or shape with a view to specific applications or uses: uniquely. To control the EAF melting process accurately, the operator uses the furnace control panel. Located on this panel is a set of potentiometers, which are used to vary the power of each phase. These potentiometers are linked to the DM. Some older furnace controls require an intermediate step to effectively control demand. Due to the age of the operator control panels in Plants 1 and 2, a parallel set of potentiometers had to be installed to allow furnace power demand reduction. Plant 3 was fitted with a controller that does not require the additional set of potentiometers. Both the DM and furnace controllers are able to reduce power via a pre-defined set-point set-point (set´point) the target value of a controlled variable that is maintained physiologically by bodily control mechanisms for homeostasis. . When the DM calls for a power reduction, it bypasses the operator potentiometers, sending the analog signal An analog or analogue signal is any time continuous signal where some time varying feature of the signal is a representation of some other time varying quantity. It differs from a digital signal in that small fluctuations in the signal are meaningful. directly to the furnace controller. The DM system is designed in a "normally closed In electronics, a normally closed switch is one that normally allows current to flow and which prevents current flow when it is perturbed.
put differently , if the DM system should ever lose power or fail in any way, it will allow the furnace to return to operational status with control going to the existing potentiometers. Each DM requires a connection to the plant Ethernet Ethernet Telecommunications networking protocol introduced by Xerox Corp. in 1979. It was developed as an inexpensive way of sending information quickly between office machines connected together in a single room or building, but it rapidly became a standard computer , which allows any personal computer with security clearance An administrative determination by competent authority that an individual is eligible, from a security stand-point, for access to classified information. in the facility to access the DM. Each DM requires one IP address on the plant network for the operator station and two for the DM system. Case Histories Show Cost Savings The three plants achieved cost savings through the reduction of power demand throughout the monthly billing period. Depending on the demand time period and kilowatt-hour kil·o·watt-hour n. Abbr. kWh or kW-hr A unit of electric energy equal to the work done by one kilowatt acting for one hour. (kWh) set-points, savings varied. Off-peak and partial-peak can be billed differently depending on the maximum demand in the monthly billing cycle Billing cycle The time elapsed between billing periods for goods sold or services rendered. . For example, if during the month of June June: see month. the off-peak period had a demand of 2,700 kWh, and partial-peak had a demand of 2,600 kWh, the maximum demand rate is $3.24 per kW for the off-peak demand period and $2.62 per kW for the partial-peak period. The same is true in reverse. If power demand during the partial-peak period were greater than that of the off-peak period, billing would be at a higher rate during the partial-peak. Plant 1 The Plant 1 EAF is supplied power separate from the rest of the plant's electrical supply. The Plant 1 DM was installed in May of 2005. Melts were operated during the off-peak and partial-peak rate periods only. The current set-points were 2,000 kWh for off-peak, 1,900 kWh for partial-peak and 200 kwh for on-peak demand. The low on-peak set point was to prevent the EAF from operating during that period. The rate for on-peak demand per kW was $11.65. After the Plant 1 DM had been operational for three months, cost savings were calculated by comparing non-controlled demand with controlled demand. Using the previous year's power demand as a baseline The horizontal line to which the bottoms of lowercase characters (without descenders) are aligned. See typeface. baseline - released version , kW reduction was calculated. Viewing the off-peak (Table 1) and partial-peak (Table 2) demand table, you can see the monthly demand savings. By adding the annual savings from off-peak and partial-peak, a total yearly power demand savings of $20,373 is shown. The final cost of the DM and installation was $54,362. Plant 1 would achieve equipment purchase payback Payback The length of time it takes to recover the initial cost of a project, without regard to the time value of money. 2.5 years from the time of installation at that rate. Plant 2 The Plant 2 EAF is supplied power by the same metered circuit as the rest of the plant. In this case, the DM has a base load of the plant's auxiliary equipment. Plant 2 had its DM installed in June of 2004 with varied results. The current set-points for Plant 2 were 2,760 kWh for off-peak, 2,370 kWh for partial-peak and 2,800 kWh for on-peak demand. This high on-peak set-point was only used when melting into that demand period. Normally, the on-peak set-point is set just above the demand baseline. This is to prevent the DM from trying to control the building's auxiliary equipment with the EAF control panel. To prove how fast a peak demand charge can escalate es·ca·late v. es·ca·lat·ed, es·ca·lat·ing, es·ca·lates v.tr. To increase, enlarge, or intensify: escalated the hostilities in the Persian Gulf. v.intr. , look at the months January January: see month. through May 2005 (Tables 3, 4 and 5). During these months, mechanical failures occurred to the potentiometer control panel. Within a few seconds, power demand broke out of the set points. The uncontrolled demand within those few seconds became the demand charge for the month. To correct the problem, programming modifications were made to the control panel, and no breakouts occurred after June. Plant 2 melting is the only EAF in operation during the peak demand period. Melting was performed during the summer months of May through August. During this period, the demand charge was $11.65 per kW. The DM creates even greater savings when used during this period. Adding the annual savings from the off-peak (Table 3), partial-peak (Table 4) and on-peak (Table 5) demand cycles, the plant realized a total yearly power demand savings of $24,316. The final cost of the DM and installation was $ 56,195. At that annual savings rate Savings rate Personal savings as a percentage of disposable personal income. , the equipment purchase payback would occur 2.3 years from the time of installation. Plant 3 Plant 3 power also is supplied by the same metering circuit as the rest of the plant. The DM was installed into this plant in May 2005. The current set-points for the Plant 3 DM were 2,800 kWh for off-peak, 2,700 kWh for partial-peak and 1,200 kWh for on-peak demand. Again, the 1,200 kWh set-point for on-peak demand was to keep the DM from trying to reduce the plant's auxiliary equipment via the EAF controls. Because this plant has a more modern furnace controller, a more aggressive power reduction was possible. The annual savings from the off-peak (Table 6) and partial-peak (Table 7) demand periods yielded a total yearly power demand savings of $25,519. The final cost of the DM and installation was $39,972. The equipment purchase payback for this plant would occur 1.5 years following the installation, given that annual savings rate. Power demand was controlled actively in these three plants, resulting in significant savings. Each DM system made small demand reductions during the highest power demand to achieve savings. Higher power Higher power is a term used in a 12-step program, such as Alcoholics Anonymous, to describe "a power greater than yourself." Although many participants equate their higher power with God, a belief in God or in formal religion is not mandatory; the higher power is intended as a demand savings resulted with more aggressive set-points. This article was adapted from a paper presented at the Steel Founders' Society of America America [for Amerigo Vespucci], the lands of the Western Hemisphere—North America, Central (or Middle) America, and South America. The world map published in 1507 by Martin Waldseemüller is the first known cartographic use of the name. 2005 Technology and Operating Conference, November 2005, Chicago Chicago, city, United States Chicago (shĭkä`gō, shĭkô`gō), city (1990 pop. 2,783,726), seat of Cook co., NE Ill., on Lake Michigan; inc. 1837. . For More Information "Combating Energy Bills," E. HuangFu, R. Naranjo Naranjo [nah-RAHN-ho] is a Spanish-language surname that can refer to: People
Robert Robert, Henry Martyn 1837-1923. American army engineer and parliamentary authority. He designed the defenses for Washington, D.C., during the Civil War and later wrote Robert's Rules of Order (1876). Noun 1. Murillo is the plant engineer for Pacific Steel Casting Co., Berkeley, Calif.
Table 1. Off-Peak Demand for Plant 1
Off-Peak
Status of DM Date Demand Set-Point
Not Installed Apr. '06 2,203 2,000
Not Installed Mar. '06 2,200 2,000
Not Installed Feb. '06 2,342 2,000
Not Installed Jan. '06 2,480 2,000
Not Installed Dec. '05 2,187 2,000
Not Installed Nov. '05 2,311 2,000
Not Installed Oct. '05 2,394 2,000
Not Installed Sep. '05 2,324 2,000
Not Installed Aug. '05 2,182 2,000
Operational Jul. '05 2,012 2,000
Operational Jun. '05 2,191 2,200
Operational May '05 2,250 2,250
Reduction
with
Current Demand Monthly
Status of DM Set Point Reduction Savings
Not Installed 203 xxx $794
Not Installed 200 xxx $524
Not Installed 342 xxx $896
Not Installed 480 xxx $1,555
Not Installed 187 xxx $606
Not Installed 311 xxx $1,008
Not Installed 394 xxx $1,277
Not Installed 324 xxx $849
Not Installed 182 xxx $590
Operational xxx 230 $745
Operational xxx 160 $419
Operational xxx 86 $225
Table 2. Partial-Peak Demand for Plant 1
Partial-
Peak
Status of DM Date Demand Set-Point
Not Installed Apr. '06 2,203 1,900
Not Installed Mar. '06 2,209 1,900
Not Installed Feb. '06 2,437 1,900
Not Installed Jan. '06 2,261 1,900
Not Installed Dec. '05 2,133 1,900
Not Installed Nov. '05 2,174 1,900
Not Installed Oct. '05 2,255 1,900
Not Installed Sep. '05 2,358 1,900
Not Installed Aug. '05 2,120 1,900
Operational Jul. '05 1,906 1,900
Operational Jun. '05 2,241 2,240
Operational May '05 2,280 2,280
Reduction
with
Current Demand Monthly
Status of DM Set Point Reduction Savings
Not Installed 303 xxx $982
Not Installed 309 xxx $1,001
Not Installed 537 xxx $1,740
Not Installed 361 xxx $946
Not Installed 233 xxx $610
Not Installed 274 xxx $718
Not Installed 355 xxx $930
Not Installed 458 xxx $1,484
Not Installed 220 xxx $576
Operational xxx 444 $1,163
Operational xxx 125 $405
Operational xxx 102 $330
Table 3. Off-Peak Demand for Plant 2
Off-Peak
Status of DM Date Demand Set-Point
Operational Jul. '05 2,808 2,800
Operational Jun. '05 2,966 2,960
Break-Out May. '05 3,310 2,960
Break-Out Apr. '05 3,036 2,960
Break-Out Mar. '05 3,312 2,960
Break-Out Feb. '05 3,314 2,960
Break-Out Jan. '05 3,276 2,960
Operational Dec. '04 3,084 3,100
Operational Nov. '04 3,041 3,100
Operational Oct. '04 3,007 3,050
Operational Sep. '04 3,050 3,000
Operational Aug. '04 3,079 3,022
Operational Jul. '04 3,252 3,280
Operational Jun. '04 3,264 3,260
Demand Monthly
Status of DM Reduction Savings
Operational 474 $1,536
Operational 311 $1,008
Break-Out 0 $0
Break-Out 0 $0
Break-Out 0 $0
Break-Out 0 $0
Break-Out 0 $0
Operational 305 $799
Operational 236 $765
Operational 271 $710
Operational 305 $988
Operational 290 $1,050
Operational 0 $0
Operational 25 $91
Table 4. Partial-Peak Demand for Plant 2
Partial-
Peak
Status of DM Date Demand Set-Point
Operational Jul. '05 2,808 2,800
Operational Jun. '05 2,952 2,960
Break-Out May. '05 3,178 2,960
Break-Out Apr. '05 3,089 2,960
Break-Out Mar. '05 3,288 2,960
Break-Out Feb. '05 3,264 2,960
Break-Out Jan. '05 3,230 2,960
Operational Dec. '04 3,103 3,100
Operational Nov. '04 2,993 3,100
Operational Oct. '04 3,041 3,050
Operational Sep. '04 3,007 3,000
Operational Aug. '04 3,025 3,022
Operational Jul. '04 3,282 3,280
Operational Jun. '04 3,263 3,260
Status of DM Demand Monthly
Reduction Savings
Operational 432 $1,132
Operational 336 $1,089
Break-Out 0 $0
Break-Out 0 $0
Break-Out 0 $0
Break-Out 0 $0
Break-Out 0 $0
Operational 233 $610
Operational 319 $1,034
Operational 319 $1,034
Operational 377 $1,221
Operational 263 $689
Operational 102 $267
Operational 25 $66
Table 5. On-Peak Demand for Plant 2
Status of DM Date On-Peak Set-Point
Demand
Operational Jul. '05 2,803 2,805
Operational Jun. '05 2,962 2,960
Break-Out May. '05 3,281 2,960
Break-Out Apr. '05 0 0
Break-Out Mar. '05 0 0
Break-Out Feb. '05 0 0
Break-Out Jan. '05 0 0
Operational Dec. '04 0 0
Operational Nov. '04 756 800
Operational Oct. '04 773 800
Operational Sep. '04 760 800
Operational Aug. '04 761 800
Operational Jul. '04 719 800
Operational Jun. '04 3,012 3,051
Status of DM Demand Monthly
Reduction Savings
Operational 324 $3,775
Operational 281 $3,274
Break-Out 0 $0
Break-Out 0 $0
Break-Out 0 $0
Break-Out 0 $0
Break-Out 0 $0
Operational 0 $0
Operational 0 $0
Operational 0 $0
Operational 0 $0
Operational 0 $0
Operational 0 $0
Operational 273 $3,180
Table 6. Off-Peak Demand for Plant 3
Off-Peak
Status of DM Date Demand Set-Point
Not Installed Apr. '06 3,374 2,800
Not Installed Mar. '06 3,341 2,800
Not Installed Feb. '06 3,331 2,800
Not Installed Jan. '06 3,346 2,800
Not Installed Dec '05 3,185 2,800
Not Installed Nov. '05 3,101 2,800
Not Installed Oct. '05 3,194 2,800
Not Installed Sep. '05 3,194 2,800
Not Installed Aug. '05 3,182 2,800
Operational Jul. '05 3,034 3,050
Operational Jun. '05 3,098 3,100
Operational May '05 3,276 3,275
Reduction
with
Current Demand Monthly
Status of DM Set Point Reduction Savings
Not Installed 574 xxx $0
Not Installed 541 xxx $1,417
Not Installed 531 xxx $1,391
Not Installed 546 xxx $1,769
Not Installed 385 xxx $1,247
Not Installed 301 xxx $975
Not Installed 394 xxx $1,277
Not Installed 394 xxx $1,032
Not Installed 382 xxx $1,238
Operational xxx 268 $868
Operational xxx 274 $718
Operational xxx 99 $321
Table 7. Partial-Peak Demand for Plant 3
Partial-
Peak
Status of DM Date Demand Set-Point
Not Installed Apr. '06 3,343 2,800
Not Installed Mar. '06 3,233 2,800
Not Installed Feb. '06 3,362 2,800
Not Installed Jan. '06 3,310 2,800
Not Installed Dec. '05 3,228 2,800
Not Installed Nov. '05 3,230 2,800
Not Installed Oct. '05 3,228 2,800
Not Installed Sep. '05 3,290 2,800
Not Installed Aug. '05 3,274 2,800
Operational Jul. '05 2,962 3,000
Operational Jun. '05 3,098 3,100
Operational May '05 3,154 3,160
Reduction
with
Current Demand Monthly
Status of DM Set Point Reduction Savings
Not Installed 543 xxx $1,423
Not Installed 433 xxx $1,134
Not Installed 562 xxx $1,472
Not Installed 510 xxx $1,336
Not Installed 428 xxx $1,121
Not Installed 430 xxx $1,127
Not Installed 428 xxx $1,121
Not Installed 490 xxx $1,284
Not Installed 474 xxx $1,242
Operational xxx 340 $891
Operational xxx 274 $888
Operational xxx 86 $225
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