Customer Engagement
Business Practices | Connections to the Grid
Who are ATC’s customers?
While we work with the general public, landowners and other stakeholders on our projects, we do not directly serve the general public.
Our customers include:
- local electric distribution companies, municipal utilities and cooperative utilities that procure primary network transmission service and are interconnected or plan on interconnecting to the ATC transmission system
- local and national marketers, generators and utilities that procure primarily point-to-point transmission service
- generators and other transmission systems that wish to interconnect with ATC’s transmission system
Our stakeholders include:
- our customers, their retail and wholesale customers
- state and federal regulators
- state and federal agencies
- independent power producers and their developers
- landowners
- general public
ATC’s priorities with all of our customers and their end-users, is to consistently
- serve the needs of our customers with expertise
- conduct our business fairly and honestly
- solicit a diversity of opinions to achieve better business results
Our customer engagement and interconnection solutions staff is dedicated to serving the needs of our customers. Please contact us with any questions, comments or concerns by emailing us at customerrelations@atcllc.com.
Business Practices
Each of the utilities involved in the formation of ATC contributed its own methods and standards of how work in the field was accomplished. ATC’s Business Practices describe how ATC and its interconnected customers deal with costs, roles and responsibilities for specific technical or business-related issues. They are created by soliciting input from internal and external stakeholders, while balancing the needs and concerns of ATC and its customers. They provide clear and consistent guidelines to allow ATC to provide timely, cost-effective and comparable service to all customers. View ATC’s Business Practice development process
Business Practice Documents
Connections to the Grid
The transmission system provides a pathway for power among interconnected power producers, or generators, and distribution companies, or load. ATC actively coordinates with MISO and the interconnected entity to develop and implement both new interconnections and modifications to existing interconnections.
MISO administers all interconnections of new generation directly to the ATC transmission system. The ATC Generating Facility Interconnection Guide (updated on March 12, 2025) supplements MISO’s requirements and describes ATC’s minimum requirements for the connection of such generation.
Inverter-Based Resource PSCAD Model Verification
ATC requires that all PSCAD plant models submitted to ATC use the ATC test controller component as the system equivalent. The interconnection customer submitting the PSCAD plant model must use the ATC test controller to complete the ATC PSCAD Model Verification Checklist. The checklist must show that the PSCAD plant model meets all ATC PSCAD modeling requirements for ATC to accept the PSCAD plant model. The ATC PSCAD Plant Model Verification Procedure is provided in here.
Generator Material Modification Study Review Prior to Commercial Operation
ATC requires generator interconnection customers to follow the instructions in the ATC Area Generator Material Modification Study Review Template when submitting a generator material modification study to MISO prior to commercial operation. Please refer to MISO’s Tariff Attachment X Section 4.4 for more information on generator modification process prior to commercial operation.
Existing Generating Facilities Modification
While MISO’s Tariff generator interconnection process may not specifically apply to modifications made to existing generators or associated interconnections, ATC requests that generator owners communicate with ATC for review of proposed modifications that are reasonably anticipated to impact the ATC transmission system. To communicate a planned change to a generating unit please complete Generating Facilities Modification Notification Form in an email to GIOANotices@atcllc.com. Please include any pertinent documentation that will assist ATC in the evaluation of the proposed modifications.
Storage Interconnection Requests
For Transmission Connected Storage facilities, transmission service is required for the facility to charge from the transmission system. If a generator owner wishes to charge their storage facility from the transmission system utilizing Network Integrated Transmission Service (NITS), ATC requests that a Storage Interconnection Request Form (SIRF) (published on 4/21/25) be submitted via email to GIOANotices@atcllc.com. Upon receiving the SIRF, ATC’s planning team will perform a system impact study to determine the impact on the ATC transmission system and, if necessary, develop solutions with the generator owner.
Resource developers: Let us help you connect to the grid
ATC has unmatched experience connecting new generation resources to the grid and recently began offering a total turn-key transmission interconnection solution to generation developers. Click here to learn more.
The ATC Transmission Interconnection Guide (updated on January 31, 2025) supplements MISO Business Practices for transmission interconnections, describing ATC’s role along with specific guidance for design, construction and operational aspects of a transmission interconnection project.
ATC requests that neighboring transmission owners communicate with ATC for review of proposed new interconnections or modifications to existing interconnections that are reasonably anticipated to impact the ATC transmission system by completing and attaching the Transmission Interconnection Request Form (TIRF) (updated on September 13, 2024) in an email to T-DLIRFS@atcllc.com.
ATC Load Interconnection Guide (updated on February 12, 2025) describes ATC’s minimum requirements and process for the connection of load to ATC’s transmission system.
ATC requests that distribution companies communicate to ATC for review of proposed new interconnections or modifications to existing interconnections that are reasonably anticipated to impact the ATC transmission system. To request a new load interconnection or a modification to an existing load interconnection, please complete and attach the Load Interconnection Request Form (LIRF) (updated September 13, 2024), in an email to T-DLIRFS@atcllc.com.
Distributed Energy Resource (DER) Request Form (updated September 13, 2024)
Queue (updated May 2, 2025)
Sectionalizing Device Flowchart (v1, published February 12, 2025)
Joint Best Value Planning White Paper (updated April 24, 2023)
ATC Generator Modeling Decision Methodology (updated November 22, 2022)
Asset Modification Form
Distribution Line
Distribution Substation
ATC Communication Infrastructure Interconnection Guide (published December 20, 2021) describes ATC’s minimum requirements and guidance to enable development and completion of communication infrastructure interconnections that consistently satisfy the needs of both ATC and its Customers. The minimum facility requirements described herein are consistent with ATC and industry best practices.
ATC requests that distribution companies communicate with ATC for the review of proposed new communication infrastructure interconnections or modifications to existing interconnections that are reasonably anticipated to impact the ATC communication system by submitting an online form requesting an interconnection as described in the ATC / LDC Shared Communication Infrastructure Agreements Business Practice.
TOP-003 Data Specification
- Pursuant to NERC Reliability Standard TOP-003, ATC, as a NERC-registered Transmission Operator (TOP), has a document specification for data needed to support Real-time monitoring, Operational Planning Analyses, and Real-time Assessment of its TOP Area (Current version – ATC’s TOP-003 Data Specification Version 2, effective April 1, 2023)
Outage Communication
- FM-9120- Protective Relay, RTU, or Communication Channel Testing Request Form (for IEs without TOA access)
- IEs should complete this form whenever they plan to disable or remove from service an IE-owned protection scheme that provides protection of ATC-owned equipment.
- Outage Request Form and Instructions (for IEs without TOA access)
- IEs should complete this form whenever they need clearance on ATC-owned equipment.
- Completed forms should be emailed to atcoutages@atcllc.com for review.
Facility and Equipment Testing Communication
- Generator Testing Request Form (Updated May 13, 2025)
IEs should complete this form such that reactive power testing can be coordinated between ATC and interconnected generating facilities.- Please review the Generator Test Process for more information on the communication and coordination of these requests. (Updated July 6, 2022)
- Completed forms should be emailed to RTORequests@atcllc.com for review.
- Coordination of Testing of Interconnected Entity (IE) Equipment:
The Interconnected Entity Testing Guide (GD-2001) is available to assist in identifying risk associated with this work. IEs should contact ATC account manager for assistance with risk identification and further address any identified risk whenever they plan to test equipment in the following types of substations:- All substations where generation is connected to the transmission system.
- All distribution substation with protection schemes that trip ATC-owned circuit breakers, circuit switchers or lockout relays, or distribution substations that have equipment connected to ATC-owned bus differential schemes.