요약하자면, 미국 에너지부에서 이 주제에 대해 가장 많이 인용되고 알려진 연구는 전기차의 빠른 도입이 지역 전력망에 조금 더 많은 투자를 필요로 하지만 사람들이 생각하는 것보다 훨씬 적은 비용이 들 것이라고 결론지었습니다. 또한 전력의 지능적인 활용이 이 투자에서 30%를 절약하는 데 도움이 될 수 있음을 나타냈습니다. 다섯 개 주를 포함한 연구에서 저자들은 2027년부터 2032년까지 비관리형 충전의 배급 비용이 약 $2.3억 달러, 관리형 충전의 경우 $1.6억 달러로 추정했습니다. 이는 해당 기간 동안 유틸리티 회사들이 그 주에서 배급에 지출한 모든 돈의 약 3%에 해당합니다.
이 연구는 규제가 아니며 각 충전소가 새로운 변압기를 설치해야 한다는 의미도 아닙니다. 이 연구는 전기 부하 분배 및 이 목적을 위한 필요한 장비 확장에 대한 상세한 모델을 제공합니다. 이 문서는 충전소와 변전소가 업그레이드가 필요한지 추정할 때 고려해야 할 모든 핵심 측면을 포함하고 있습니다. DOE EV 충전 프로그램.
독립성에 관해서, 수비안 전기는 변압기 및 변전소 생산에 특화된 제조업체입니다. 우리는 에너지부와 연결되어 있지 않으며 DOE 연구의 모든 결과는 어떤 회사나 그 제품, 우리의 제품을 포함하여 지지를 나타내는 것으로 해석될 수 없습니다.
DOE EV 충전 배급 업그레이드 보고서가 실제로 발견한 것
연구를 수행한 사람들과 그 모델링 내용
다주 주 교통 전기화 영향 연구 보고서, 일반적으로 TEIS로 약칭되며, 2024년 3월에 발표되었고, 국립 재생 가능 에너지 연구소, 로렌스 버클리 국립 연구소 및 그리드 분석 회사인 케발라가 DOE의 지원을 받아 제작했습니다. 연구자들은 캘리포니아, 일리노이, 뉴욕, 오클라호마 및 펜실베이니아의 배급 그리드에서 전기에 대한 패키지 수준의 수요를 모델링했습니다. 이 주들은 도시와 농촌 공간, 그리드 설계, 화물 운송 기술 및 전기차 관련 정책의 다양한 조합으로 선택되었습니다.
저자들은 2027년의 두 가지 미래 상황과 2032년에 매우 유사한 또 다른 상황을 비교했습니다. 즉, 행동 시나리오에서는 차량 전기화 계획이 2023년에 고려된 연방 차량 배출 요구 사항 준수 옵션 중 하나를 통해 진행되어 2032년까지 5500만 대의 전기차가 설치될 것으로 예상됩니다. 비행동 시나리오에서는 차량 설치가 덜 효과적이며, 즉 4100만 대의 차량이 설치됩니다. 분석된 다섯 개 주에서 총 차량 수는 각각 2000만 대와 1600만 대로, 390만 대의 차이를 나타냅니다. 두 시나리오는 모두 비관리형 충전 기술로 개발되었으며, 이는 차량이 플러그를 꽂은 직후에 완전 충전 상태로 전기를 받는 것을 의미합니다.
주요 수치
아래의 모든 수치는 증가분으로, 액션 시나리오와 비액션 시나리오 간의 차이를 의미하며, 2023년 달러 기준입니다.
| 발견 | 다섯 주 결과 |
|---|---|
| 증가분 배전망 투자, 관리되지 않는 충전 (2027–2032) | 약 $2.3억 |
| 증가분 배전망 투자, 관리된 충전 | 약 $1.6억 (30% 낮음) |
| 다섯 주에서의 현재 연간 배전 투자 비율 | 약 3% |
| 증가분 그리드 자산, 관리되지 않는 충전 | 8개의 배전 변전소, 125개의 피더 및 30,000개의 서비스 변압기 |
| 관리된 충전으로 인한 자산 필요 감소 | 변전소 약 50%, 피더 약 40%, 서비스 변압기 약 30% |
| 2032년까지 필요한 증가분 충전 포트 | 3백만, 그 중 97%는 AC 포트 |
| 결합된 충전 및 그리드 투자 | $12.0억, 그 중 $9.7억은 충전 장비이고 $2.3억은 그리드 업그레이드 |
| 증가분 차량의 평생 순 소비자 이익 | $33억, 인프라 투자보다 2.5배 이상 |
보고서에서 쉽게 인식되지 않을 수 있는 두 가지 미묘한 점이 있습니다. 첫 번째는 보고서에서 연구된 상황으로, 변전소, 변압기 뱅크 및 서비스 변압기가 2027년에 건설 작업을 마치고 2032년 수요 격차를 메우는 것입니다. 피더 업그레이드는 2032년에도 여전히 진행 중입니다. 따라서 피더가 여기서 문제로 남아 있음을 알 수 있습니다. 두 번째 중요한 점은 비용이 매우 다른 주에서도 유사한 정도로 상승했다는 것입니다: 관리되지 않는 시나리오에서 전력 배급 비용은 2032년까지 3.3-4.3% 상승할 것입니다.
보고서가 알려주지 않는 것
이러한 수치를 정확하게 인용하는 것만큼이나 올바르게 해석하는 것이 중요합니다. 연구는 변전소, 피더, 변압기 및 배전선에만 집중되었습니다. 따라서 발전 및 송전 비용은 고려되지 않았습니다. 다섯 주는 좋은 이해를 제공하지만 모든 유틸리티의 모든 상황을 대표하지는 않습니다. 모델링은 가정 및 차량 차고 충전만 포함되었으며, 동일한 회로에서 다른 비EV 부하를 무시했습니다. 저자들은 절약을 보수적으로 평가합니다. 이 연구는 EV 사용자나 동일한 용량을 사용하는 다른 고객에게 그리드 요금을 할당하지 않습니다.
연구가 변압기, 피더 또는 변전소의 업그레이드 필요성을 결정한 방법
보고서에서 엔지니어에게 최대 적용 가능한 정보는 제목에 언급된 비용이 아니라 그러한 비용이 계산된 방식에 기반합니다. Kevala는 네트워크의 모든 계층에서 시간당 최대 부하를 계산하고 장비가 과부하될 때와 대체할 수 있는 것을 보여주는 명확한 규칙을 정의할 수 있었습니다.
| 그리드 수준 | 연구에서 사용된 과부하 테스트 | 모델링된 수정 |
|---|---|---|
| 배급 변전소 | 용량의 100%를 초과하는 최대 부하 | 100 MW 미만의 변전소에 30 MW 변압기 뱅크 추가, 또는 더 큰 경우 용량의 35%에 해당하는 뱅크; 여전히 과부하인 경우, 일반적으로 60 MW의 새로운 변전소를 건설 |
| 피더 | 열 용량의 100퍼센트를 초과하는 피크 부하 | 가능할 경우 인근 피더로 부하를 이전하고, 그렇지 않으면 약 11 MW(최대 15 kV), 24 MW(16~25 kV) 또는 30 MW(26~35 kV)의 새로운 피더를 추가하십시오. |
| 서비스 변압기 | DC 고속 충전을 제외한 피더의 모든 서비스 변압기의 총 피크가 결합 정격의 125퍼센트를 초과합니다. | 추가 부하를 충당하기 위해 50 kW 서비스 변압기를 추가하십시오. |
| DC 고속 충전 사이트 | DC 고속 충전이 있는 모든 사이트 | 충전기 전력, 포트 수 및 다양성 계수에 따라 크기가 조정된 전용 3상 서비스 변압기 |
연구 논문은 또한 구성 요소의 비용을 자세히 설명했습니다. 캘리포니아 2032년의 경우, 새로운 변전소를 건설하는 평균 발표 비용은 약 $30백만, 새로운 변압기 뱅크 건설 비용은 $10백만, 새로운 피더 건설 비용은 약 $611,000, 기존 유형의 서비스 변압기 비용은 약 $20,000, 고속 충전 센터 전용 서비스 변압기 비용은 $50,000입니다. 이러한 비용은 예상 비용이지만, 비용이 얼마나 빠르게 증가하고 있는지를 보여줍니다. 시간도 같은 패턴을 따릅니다. 다른 연구를 참조하면, 보고서는 3개월에서 10개월 지속되는 충전 프로젝트가 피더를 업그레이드해야 할 경우 1년을 얻을 수 있으며, 변전소 업그레이드의 경우 최대 4년을 얻을 수 있다고 언급합니다.
전기 배전 네트워크의 각 층에 대한 EV 충전의 영향
The electrical distribution network has three distinct levels and EV charging creates different forms of disruption in each one. The most valuable information for planning purposes is to know which of these levels is the bottleneck, as responses differ for each of them.
Failures of the Service Transformer
The service transformer refers to the unit mounted at either the top of a pole or resting on the ground. Its main responsibility is to transform voltage from a medium level to a low one that can be used by customers of a given community including homes or car stations. The service transformer usually serves several customers, up to about a dozen, and hence becomes the first one to encounter the issue of clustered charging stations. The transformer is based on the need to meet the demands of all residents of a community living in homes; but this solves little in case several stations of 7-11 kW power pull the trigger at the same time.
Feeder Thermal Constraints
A feeder is the medium-rated voltage circuit which usually has 12.47 KV, 13.2 KV or 24.9 KV in North America and 10, 11, 20 or 33 KV in other countries. It can run out of capacity either when its load reaches the thermal limit or when the level of voltage on the load side changes dramatically. The triggers typically include fast charging hubs, truck depots and other places of charging where one charging station consumes more power than a whole area of residential buildings.
Substation Capacity Limitations
A substation consists of two or four transformer banks. Substation operations are the least likely to be undermined by extensive home charging; however, this is one of the most expensive and time-consuming processes of upgrades.
How EV Charging Load Differs by Site Type
The same amount of energy can be easy or hard for the grid to deliver depending on how concentrated it is and when it arrives. The TEIS appendix estimates the distribution upgrade cost attributable to each type of charger, which gives a useful sense of scale.
| Site type | Typical charger power | First pressure point | Modeled grid upgrade cost per charger, 2032, unmanaged / managed |
|---|---|---|---|
| Single-family home, Level 2 | 7 to 11 kW | Shared street transformer | About $1,500 / $1,300 |
| Workplace, Level 2 | 7 to 19 kW | Building or site transformer | About $5,000 / $5,200 |
| Public fast charging, light-duty, 150 kW | 150 kW | Dedicated site transformer, sometimes the feeder | About $29,700 / $27,400 |
| Public fast charging, light-duty, 250 kW | 250 kW | Dedicated site transformer and feeder | About $48,700 / $44,200 |
| Truck depot, 150 kW DC | 150 kW | Feeder and sometimes substation | About $47,100 / $38,000 |
| Public heavy-duty charging, 1.5 MW | 1.5 MW | Feeder and substation | About $256,600 / $187,400 |
Two notable trends emerge. The price per charger increases substantially with power, and managed charging has the highest advantage when vehicles remain parked for long periods of time, such as depots, while making almost no impact at workplaces with a steady load throughout the day. This confirms the study’s major finding that the greatest savings to the grid derive from residential spaces and fleet depots where charging can be scheduled without inconveniencing the driver.
How to Size a Distribution Transformer for DC Fast Charging
Many projects either oversize their transformer or undersize it. Oversizing occurs when the nameplate ratings for every charger are summed to calculate the size leading to wastage of capital, while ignoring losses and the coincidence of chargers sizing results in undersizing. Proper sizing of DC fast charging transformers occurs between these two extremes since it relies on clearly defined assumptions.
Charger Nameplate vs Real Grid Demand
Normally a charger will be rated for DC output. But since the grid must supply that output along with conversion losses, the AC input must be greater in value than the DC rating. In addition, not all chargers deliver their full power at any time as vehicles come at different levels of charge and charging power is reduced when the battery is filled. A lot of the sites also have a system-level limit and share power among the dispensers.
Diversity Factors Used in the DOE Study
The TEIS team sized each fast-charging site’s dedicated transformer by multiplying charger power and port count by a diversity factor that depends on charger size, vehicle class and the number of ports. For light-duty sites, the factors were:
| Charger power per port | Up to 3 ports | 4 to 8 ports | More than 8 ports |
|---|---|---|---|
| 50 kW | 1.0 | 1.0 | 1.0 |
| 150 kW | 1.0 | 1.0 | 0.5 |
| 350 kW | 1.0 | 0.75 | 0.5 |
| 500 kW | 1.0 | 0.75 | 0.5 |
It was assumed that small sites would operate at full capacity, while diversity only came into play on larger sites with high-capacity charger installations. The considerations are only assumptions in modeling, but they are a good verification tool to validate one’s own calculations. In the USA, article 625 of NEC puts EV chargers into the category of continuous loads and that affects the rating of both customer-side conductors and protective devices.
Worked Example: Eight 180 kW DC Fast Chargers
Consider a public hub with eight 180 kW DC chargers. Assume a 70 percent coincidence factor enforced by the site’s load management, 95 percent charger efficiency, a 0.98 input power factor and a 15 percent design margin for growth and auxiliary loads such as lighting, cooling and payment systems.
| 단계 | 계산 | 결과 |
|---|---|---|
| Coincident DC output | 8 × 180 kW × 0.70 | 1,008 kW |
| AC input power | 1,008 kW ÷ 0.95 | About 1,061 kW |
| 겉보기 전력 | 1,061 kW ÷ 0.98 | About 1,083 kVA |
| With 15 percent margin | 1,083 kVA × 1.15 | About 1,245 kVA |
| Next standard size, IEC practice | Round up | 1,250 kVA |
| Next standard size, North American three-phase pad-mount | Common ANSI ratings step from 1,000 to 1,500 kVA | 1,500 kVA |
The factor of coincidence determines the parameters of the project more than anything else. If the site is run at the loading of 50%, the value will be about 889 kVA, which would require the supply of 1,000 kVA of capacity, regardless of the system. In the case of running the site under load at 100% and without load management, the required capacity is about 1,779 kVA, which would call for 2,000 kVA. This influence is the reason why load management should be determined first, rather than done after ordering the transformer. Remember that this example is just an example, not a design – real project includes the measurement of harmonics of the chargers’ power electronics, transformer impedance, and levels of short-circuit currents, ambient temperature, and electric utility regulations.
When Is a Feeder Upgrade Needed Instead of a Bigger Transformer?
A larger transformer can be useful at a site but it will not solve issues concerning an already overloaded feeder. This is a point that often confuses people as the developer owns the transformer while the utility has the control over the feeder.
An upgrade to the electrical system for electric vehicle charging will be necessary if the following three issues occur: the new load increases the electric load that the feeder can carry; voltage levels at the end of the circuit are beyond the legal limits; or according to the utility’s hosting capacity study or interconnection study, the circuit cannot accommodate the new load without any negative effect on other consumers. As for the approach taken by the Department of Energy that pioneered the idea, the utility’s representatives focused on shifting loads to the feeder that has enough capacity before they even think about building the new circuits.
Thus, one of the lessons for developers is inescapable: work on feeders usually requires more time and costs more in comparison to switching transformers, and sometimes even means that new digging or overhead work needs to be carried out on a site. There is also an idea to get in touch with the utility in advance to check on the loading capacity before making a decision to make a purchase.
Is it Possible for Managed Charging and Battery Storage To Delay Grid Improvements?
Yes, usually, and that is the main finding from the study carried out by the Department of Energy. Managed charging is meant to transfer or redistribute loads from other power sources so that existing infrastructure is able to handle the loads required. Research has indicated that managed charging can allow for a reduction in the peak electric load due to electric vehicles by about thirty percent and contribute to the need for construction of new substations, feeders, and transformers by about fifty percent, forty percent, and thirty percent respectively.
Time-of-Use Pricing and Dynamic Load Management
The most basic approach is the so-called time-of-use pricing, which means that users are incentivized to charge vehicles after the peak period in the evening. More advanced approaches allow for dynamic load management, which permits power management in real time by limiting the load in terms of performance of various charging points. In this instance, modified software can allow for effective use of transformers by distributing workload over time and limiting the total load on transformers.
Flexible Connection to the Grid
An upcoming method is the so-called flexible connection to the grid (first introduced in a paper published in 2024 by the Office of Electrical Power of the Department of Energy). This approach permits connections to charging stations before construction of facilities is completed, based on the condition that electrical charge of the facilities is reduced in fixed situations of overload. Several Californian and some northeastern states have piloted this approach and connected the electrical loading for public charging on the charging vehicle stations.
Battery Storage for Peak Shaving
A battery energy storage system is put into use at the charging station where it receives charging exposure from the grid at a slow pace when traffic is low and vice-versa where it actually discharges when activity is heavy. This enables the station to offer more power than the grid itself allows. Energy storage is useful in the locations where peak periods are short and predictable. A battery energy storage system adds its own components like a power conversion unit, devices for protection, etc. Our guide to the 에너지 저장 컴팩트 변전소 explains how the PCS, transformer and medium-voltage switchgear fit together in these projects.
When Hardware Upgrades Are Still Unavoidable
Management has limitations. If a facility has a set energy requirement each night, scheduling may help reduce the peak load but won’t lower the total consumption. Charging a battery is not possible if the load already exceeds the supply capacity since the battery can’t recharge. There is limited flexibility for a DC fast charging station that needs to serve any vehicles arriving at that time. Results from the US Department of Energy show that managed charging is not effective. In Oklahoma, where the demand peaks in the morning, postponing charging at night did not ease the situation. In this case, installing a well-sized transformer at the charging location or doing some work on the feeder is the only practical solution.
Choosing the Equipment: Pad-Mounted, Dry-Type or Prefabricated Substation
Pad-Mounted Transformers for Public Charging Sites
In the majority of outdoor charging locations, three-phase pad-mounted transformers are used as standard equipment. Such transformers are mounted on a concrete slab and have a protected enclosure so they can be put near the charging points. Important settings for selection include input voltage, loop or radial power supply, connection configuration, resistance, and effectiveness. Subian Electric manufactures three-phase pad-mounted transformers configured to each project’s network voltage and standard.
Dry-Type Transformers for Indoor and Parking Structures
In instances where invigilators are installed within the underground parking areas, underground garages, or buildings, the fire safety regulations would generally prefer isolation transformers. Hence, the most common option would be cast resin dry type transformers that do not need an oil tank at all and need minimal servicing. Subian’s 문의하기 전에 검토할 수 있습니다. 모든 공급업체로부터 구매하는 올바른 방법은 사양을 고정하고 시험 증거를 요구하며 문서화된 수치로 비교하는 것입니다. includes epoxy-resin cast units for these installations.
Prefabricated Substations for Large Charging Hubs
Medium-voltage switchgear, one or several transformers and a low-voltage board are usually required at large hubs and bus stations where charging is combined with solar and storage. A prefabricated substation manufactured in a plant provides everything in one tested enclosure and saves a lot of time when working on the site.Our compact substation guide covers how these units are specified. Subian’s YB 시리즈 조립식 변전소 integrates the three sections in one unit, and for 33 kV networks the company also builds 33 kV compact substations.
IEEE C57 vs IEC 60076 and IEC 62271-202
The two main families of standards should not be mixed, because voltages, ratings and test levels differ.
| 항목 | North American utility projects | International projects |
|---|---|---|
| 변압기 표준 | IEEE C57 series, including IEEE C57.12.34 for three-phase pad-mounted units | IEC 60076 시리즈 |
| Prefabricated substation standard | Utility and customer specifications | IEC 62271-202 |
| Typical distribution voltages | 12.47, 13.2, 24.9 and 34.5 kV | 10, 11, 20, 22 and 33 kV |
| 빈도 | 60 Hz | 50 Hz in most markets, 60 Hz in some |
| Common three-phase ratings around 1 MVA | 750, 1,000, 1,500 kVA | 800, 1,000, 1,250, 1,600 kVA |
| Approval route | Utility specification and approved vendor list | Type test reports and utility or consultant approval |
Subian Electric builds mainly to IEC standards for projects in Asia, Africa, the Middle East and Latin America. North American requirements can be engineered on a project basis, but voltage, insulation level, configuration and utility acceptance must be confirmed at the start of every enquiry.
What Drives Upgrade Costs and Lead Times?
There is a huge variation in implementation costs of charging sites, from very low in cases of present spare capacity to many millions if the expansion of a substation is required. Major factors in the overall costs of charging site implementation are transformer and switchgear itself; installation costs incurred, which usually exceed hardware costs; costs related to utility make-ready and interconnection; and completion of various reinforcement works. It is important to note that the charging cost estimations are based on TEIS documents, which do not take into account utility-side improvements or on-site storage, which is significant, according to the authors.
The person who pays the bill depends on the ownership boundary. Utility practices vary: the utility bears the costs and owns the equipment before the revenue meter (with transformer sometimes included), while the developer pays for everything behind it in some cases. In some other cases, customer is making the purchase of the needed transformer himself. The earlier the boundaries of the costs responsible for the parties at the project are checked, the fewer chances for budget surprises.
Nowadays, time matters as much as money. Demand growing from sources of renewables, data centers, and electrification can lead to expansion of transformers’ lead time in different markets. Therefore, if a project is waiting for the permits to start the process of equipment ordering, it may wait for a considerable period of time. Hence, it is better to choose standard ratings, to make sure the specifications check is done, and to involve more than one qualified manufacturer.
EV Charging Distribution Transformer RFQ Checklist
Whether you are buying a single pad-mounted unit or a complete substation, sending the same clear brief to every supplier makes quotations comparable.
| 카테고리 | What to specify |
|---|---|
| 정격 | Primary and secondary voltage, frequency, rated kVA with the load calculation and coincidence assumption behind it |
| Electrical design | Vector group, impedance, basic insulation level, tap range, harmonic loading from chargers |
| 구성 | Loop or radial feed, dead-front or live-front, primary protection, LV outgoing feeders |
| Efficiency and construction | Loss limits under local regulations, insulating fluid or dry-type construction |
| Site conditions | Ambient temperature, altitude, corrosion and flood risk, enclosure protection |
| Standards and documents | IEEE C57 or IEC 60076, routine test reports, type test evidence, drawings |
| 상업적 | Delivery time, packing, warranty, commissioning support |
자주 묻는 질문
What does the DOE EV charging distribution transformer and feeder upgrades report say?
The Multi-State Transportation Electrification Impact Study published in 2024 projected that an additional $2.3 billion distribution investment was required across five states from the year 2027 to the year 2032 with the adoption of unmanaged charging that included 8 substations, 125 feeders and 30,000 service transformers. The amount required to invest in the distribution with managed charging decreased to around $1.6 billion.
Does EV charging always require a transformer upgrade?
No. In most cases, the connections to the home and small sites remain the same. Upgrades may occur where multiple chargers share a single service transformer, where a site implements high-power DC fast charging, or where a fleet depot has numerous vehicles in one location.
What size transformer does a DC fast charging station need?
Charging capacity is determined by the number of chargers, coincidence factor, efficiency as well as power factor. In the example mentioned above, eight 180 kW chargers which have a coincidence of 70 percent require about 1,245 kVA, which amounts to 1,250 kVA as per IEC standard and 1,500 kVA according to standard North American specifications.
Can managed charging avoid a feeder upgrade?
There are times when it happens. The research conducted by DOE proved the reduction of the feeder requirements by approximately 40 percent. Changing or limiting loads helps contain peaks of the load within the feeder’s limits. With versatile connections, some installations can connect before the upgrade is finished, however, an installation with energy demand exceeding the level must be upgraded.
Can battery storage replace a transformer upgrade?
Battery storage can cover short, predictable peaks and let a site deliver more charging power than its connection allows. It cannot replace an upgrade when the site’s average load is already close to or above its grid connection.
Are DOE transformer efficiency standards the same topic?
No. The TEIS document is a grid planning report. The Department of Energy is responsible for the implementation of minimum efficiency standards for distribution transformers sold in the United States through rules issued in 2024 to come into force in 2029. Each is relevant to buyers, however, they are not the same.
참고 문헌
- U.S. Department of Energy: Multi-State Transportation Electrification Impact Study (2024)
- National Renewable Energy Laboratory: Transportation Electrification Impact Study results
- U.S. Department of Energy Office of Electricity: Flexible DER and EV Connections (2024)
- Alternative Fuels Data Center: Procurement and Installation for EV Charging Infrastructure
- 배전 변압기, 위키백과
The DOE research makes one point clear: grids can support large-scale EV charging, provided the right equipment is planned in the right place and load is managed sensibly. When your charging hub, fleet depot or parking project needs a transformer or substation, Jiangsu Subian Electric Power Equipment Co., Ltd. designs and builds pad-mounted and dry-type transformers, prefabricated substations and new energy substations for charging and storage projects, configured to your network voltage and standard. For private-label or distributor supply, see our OEM 및 ODM 프로그램. Send your charger list, network voltage and site conditions through our 연락처 페이지, and our engineers will reply with a sizing check, drawings and a factory quotation.