Oncor Application
v12-29-2015
Generation Paralleling Less than 100 milliseconds
This application is for generation that utilizes transfer switches that have what is
typically referred to as “make before break” type switching. This type of switch transfers
power sources, say from generator to utility, in less than 100 milliseconds. With this
type of switching, “loads” see a continuous source of power when transferring from one
source to an alternate source.
Generally switching systems that parallel for less than 100 milliseconds are classified
into two typical types. For purposes of discussion let’s define Type 1 and Type 2
classifications:
Type 1 – Systems utilizing pre-manufactured switches with standardized control logic
processing schemes. This type of design utilizes standard factory ordered switches
from a manufacturer and generally is for voltages up to 600 VAC. These switches are
specified to meet various certifications such as UL, NFPA, NEC and ISO ratings.
Typically switches may be sourced with multiple generators with total generation
capacities of less than 2,500 kW per switch and are located downstream of the
customers main breaker.
Type 2 – Traditional switchgear utilizing breakers with custom designed PLC logic and
breaker switching schemes.
THIS APPLICATION IS FOR TYPE 1 DESIGNS WITH GENERATION CAPACITIES
LESS THAN 2,500 KW. Customers utilizing traditional switchgear with customized
programmed logic and PLC controls will need to utilize Oncor’s application for
Generator Paralleling Longer than 100 milliseconds.
General Process
 Oncor receives and reviews the completed application.
 Oncor typically does not perform an Impact Study for Type 1 systems less than
2,500 kW and does not charge a Study Fee. Type 1 systems utilizing more than
one transfer switch will be assessed a Study fee. Consult Oncor for more
information.
 Oncor prepares, submits and secures an Interconnection Agreement from
customer.
 Final approval is granted when the Interconnection Agreement is signed by both
Oncor and the Customer and when Oncor does not object to the written field test
report (from the field test engineer or P.E. of record) indicating the shunt trip
circuits and/or other protective functions have been installed and tested.
General Information:
1) Information Submittal Format - Information requested in this application can
be submitted in multiple forms. Please feel free to just mark, “see
attached” or “already provided” should you wish to submit the requested
information in a different form or if information has already been provided.
2) This application may be faxed, scanned or mailed to Oncor. Applications
submitted by email larger than 8MB will be rejected by Oncor servers.
3) The Distributed Generation Pre-Interconnection Study Fee schedule states
the terms, “network” and “pre-certified.” Pre-certified typically refers to UL1741 for inverter technologies and network refers to downtown grids found
in Dallas and Fort Worth. This application is normally classified as “Not
pre-certified.”
4) Generator dynamic modeling values are not needed for Type 1 application
designs.
Application Check List
Yes No
Completed Interconnection Application 6.3.3 (pages 2-3 following)
Completed Supplement to Application 6.3.3?
Did you provide the One-line diagram?
Did you provide shunt trip control circuits?
Questions related to this application can be directed to:
Ken Brunkenhoefer
brunkenhoefer@oncor.com
Julio Chavarria
julio.chavarria@oncor.com
214 743 6829
214 743 6840
Tariff for Retail Delivery Service
Oncor Electric Delivery Company LLC
6.3 Agreements and Forms
Applicable: Entire Certified Service Area
Effective Date: September 25, 2011
Sheet: 3
Page 1 of 2
Revision: Two
6.3.3 Application for Interconnection and Parallel Operation of Distributed
Generation with the Utility System
Return Completed Application to:
Oncor Electric Delivery Company LLC
Attention: Distributed Resource Specialist
1616 Woodall Rodgers Fwy
Dallas, TX 75202-1234
Customer’s Name: _____________________________________________________________________________________________
Mailing Address: ______________________________________________________________________________________________
Contact Person: _______________________________________________________________________________________________
Telephone Number and email address: _____________________________________________________________________________
Service Point Address: __________________________________________________________________________________________
Information Prepared and Submitted By: ____________________________________________________________________________
(Name and Address) ___________________________________________________________________________________________
Signature ____________________________________________________________________
The following information shall be supplied by the Customer or Customer’s designated representative. All applicable items must be accurately
completed in order that the Customer’s generating facilities may be effectively evaluated by Company for interconnection with the utility system.
GENERATOR
Number of Units:
Manufacturer:
Type (Synchronous, Induction, or Inverter): __________________________________________________________________________
Fuel Source Type (Solar, Natural Gas, Wind, etc.): ____________________________________________________________________
Kilowatt Rating (95 F at location) __________________________________________________________________________________
Kilovolt-Ampere Rating (95 F at location): ___________________________________________________________________________
Power Factor: _________________________________________________________________________________________________
Voltage Rating: ________________________________________________________________________________________________
Ampere Rating: ________________________________________________________________________________________________
Number of Phases: _____________________________________________________________________________________________
Frequency: ___________________________________________________________________________________________________
Do you plan to export power: ________Yes ________No
If Yes, maximum amount expected: ________________________________________________________________________________
Pre-Certification Label or Type Number ___________________________________________________________________________
Expected Energizing and Start-up Date: ____________________________________________________________________________
Tariff for Retail Delivery Service
Oncor Electric Delivery Company LLC
6.3 Agreements and Forms
Applicable: Entire Certified Service Area
Effective Date: July 1, 2011
Sheet: 3
Page 1 of 2
Revision: Two
Normal Operation of Interconnection: (examples:, provide power to meet base load, demand management, standby, backup, other (please describe)__________________________________________________________________
One-line diagram attached: ________Yes
Has the generator Manufacturer supplied its dynamic modeling values to the Host Utility? _________ Yes
[Note: Requires a Yes for complete application. For Pre-Certified Equipment answer is Yes.]
Layout sketch showing lockable, “visible” disconnect device: _________Yes
Authorized Release of Information List
By signing this Application in the space provided below, Customer authorizes Oncor to release Customer’s proprietary information to
the following persons:
Name
Phone Number
E-Mail Address
Owner / Customer
Project Manager
Electrical Contractor
Consultant
If Customer does not sign this Application, then Customer must authorize Oncor to release Customer’s proprietary
information to consultant or contractor. For residential Customers, that authorization may be provided in an e-mail
communication or in hard copy. For commercial Customers, that authorization must be made on the Customer’s business
letterhead.
_______________________________
[CUSTOMER NAME]
BY: ___________________________
TITLE: _________________________
DATE: _________________________
Supplement to Application 6.3.3 Interconnection
Application for Parallel Operation Less than 100 milliseconds
1. Owner of Generation Resource
Please indicate for use in the Interconnection Agreement the name and type of entity who is the owner of
the distributed resource:
Legal Name of the Owner of Renewable System
Legal Name
Type of Entity
DBA (if applicable)
Following are examples of names and types of entities:
XYZ Business Inc.
XYZ Company LLC
City of XYZ
XYZ ISD
XYZ Business LP
XYZ Business LTD
XYZ Organization
XYZ financial institution N.A.
a Texas corporation
a Delaware limited liability company
a Texas governmental agency
a Texas non-profit organization
a Texas limit partnership
a Texas limit partnership
a Texas non-profit organization
member FDIC
DBA XYZ High School
2. Account ID and Address Information
Yes
New Service
Is this application for a new service account?
If Yes, then provide proposed service address
Service Address:
City:
State:
Zip:
If No, the please provide existing account information:
Existing Service Accounts
Please provide 17 digit ESI ID:
Normally provided on electric bill.
ESI ID – Oncor
OR
Oncor Company
Premise ID#
st
Code (1 10 digits) ( last 7 digits)
1044372000
ESI ID – (formerly SESCO)
1017699000
No
Yes
No
Is this ESI ID for a temporary service?
Oncor Meter Number (optional if ESIID not provided)
Service Address:
City:
State:
Zip:
Official Notices Address for Interconnection Agreement
Is the mailing address for the Agreement the same as your service address?
Yes
No
Notices Mailing Address:
City:
State:
Zip:
3. Oncor Delivery Voltage Information
Please indicate the Oncor delivery voltage:
120/240 v, 1 phase, 3 wire
277/480 v, 3 phase, 4 wire
7,620/13,200 v, 3 phase, 4 wire
120/240 v, 3 phase, 4 wire
2,400/4 160 v, 3 phase, 4 wire
14,400/24,900 v, 3 phase, 4 wire
120/208 v, 3 phase, 4 wire
7,200/12,470 v, 3 phase, 4 wire
Other:
4. Switchgear – Generator Information
Transfer Switch Information
Model
Manufacturer
Quantity
Generator Information
Model
Manufacturer
Quantity and Size
5. General Information
1) Statement from manufacturer (or registered professional engineer) that switchgear will
operate in less than 100 milliseconds.
2) State the technology utilized for switching (hard wire controls using breakers and PLCs,
PLC logic using contactors, etc.)
3) Please provide the default or intended user selectable settings for the identified switch
(i.e., under-voltage and overvoltage pickup, under and over frequency pickup, sync check
windows for voltage, phase and slip, etc.) Attached in the Appendix of this document are
Oncor’s minimum required settings for voltage and frequency for your use with selecting
these settings.
4) Please provide the “breaker failure to close or open” fail safe protection scheme provided
in the switch. Scheme should indicate monitoring closed transition times which should
result in automatic opening of switches or breakers when transition times equal or exceed
100 milliseconds.
5) Oncor requests verification that shunt trip circuits have been installed. Control wiring
diagrams are requested to confirm installation and a confirmation statement from a
registered professional engineer or qualified installation contractor is required stating the
shunt trip circuits have been installed and tested.
Did you provide control wiring diagrams with this
Yes
No
application?
What is the expected date for field commissioning and
testing?
Date:
Expected date the field verification test report will to be sent
to Oncor?
Date:
6) Please indicate if the switchgear has a mode of operation allowing paralleling equal to or
longer than 100 ms. If the switchgear has this operating function available, then Oncor needs
assurance that this mode has been made non-operational. Please indicate your plans to
disable this mode of operation.
Appendix
Oncor Utility Criteria for Over / Under Voltage and Frequency
Acceptable Transfer Switch Settings
Dropout below 90%
Pickup 90 – 110%
Dropout above 110%
Standard Oncor Voltage Clearing Times (minimum required)
Step 1
Pick-Up
Timing
Pick-Up
Under-voltage (27)*
90%
30 sec.
70%
Over-voltage (59)*
110%
30 sec.
116%
* Per phase sensing is required
Step 2
Timing
10 cycles
10 cycles
Standard Oncor Frequency Clearing Times – One Step (minimum required)
Pick-Up
Timing
Allowable Transfer Switch Settings
Under-frequency ( 81U )
59.3 hertz
15 cycles
Dropout under 59.4 hz. over 60.6 hz.
Over-frequency ( 81O)
60.5 hertz
15 cycles
Pickup above 59.4 hz. below 60.6 hz.