Measuring relays and protection equipment - Part 181: Functional requirements for frequency protection
Measuring relays and protection equipment - Part 181: Functional requirements for frequency protection.
IEC 60255-181:2019 specifies the minimum requirements for functional and performance evaluation of frequency protection. This document also defines how to document and publish performance test results.
This document covers the functions based on frequency measurement or rate of change of frequency measurements. It also covers frequency protection where additional blocking elements are used.
This document defines the influencing factors that affect the accuracy under steady state conditions and performance characteristics during dynamic conditions. The test methodologies for verifying performance characteristics and accuracy are also included in this document.
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Version 1 - 2026-06-22
These Terms and Conditions (the “Terms”) consist of four parts that together form a single, integrated agreement governing access to the Nimonik Online Store and the purchase and use of Products from Nimonik:
Part A — Terms and Conditions of Sale, which governs the purchase of the Product;
Part B — End Customer Licence Agreement, which governs the use of the Product;
Part C — Use of the Website and Account, which governs use of the Nimonik Online Store and applies to all users, whether or not a purchase is made; and
Part D — General Terms, which applies to Parts A, B, and C.
By placing an order for, or accessing, downloading, printing, installing, or otherwise using, a Product or the Nimonik Online Store, you accept and agree to be bound by these Terms.
The following definitions apply throughout this document, including Part A and Part B:
”Nimonik” means Document Center Inc., a California corporation, with its registered office at 401 Roland Way, Ste#224, Oakland, CA, 94621, United States.
”Nimonik Online Store” means Nimonik’s online standards store at https://standards.nimonik.com, through which Products are offered, ordered, accessed, and delivered.
”Licensee” or “you” means the purchaser or end-user of the Product.
”Product” means the standard, publication, document, or other content supplied by Nimonik, whether in electronic format or in hard-copy printed format. Any reference to the Product includes the Product in its entirety or any part thereof, as applicable.
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These T&Cs govern the purchase of Products by the Licensee from Nimonik.
By placing an order for a Product, or by accessing, downloading, installing, or otherwise using the Product, the Licensee accepts and agrees to be bound by these T&Cs and by the End Customer Licence Agreement set out in Part B. The Licensee shall ensure that it has read and understood all applicable terms before completing the purchase.
Any questions regarding these Terms may be addressed to Nimonik via https://standards-nimonik.freshdesk.com/support/tickets/new
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By placing an order for a Product, or by accessing, downloading, printing, installing, or otherwise using the Product, the Licensee accepts and agrees to be bound by this Agreement and the T&Cs. The Licensee shall ensure that it has read and understood all applicable terms before completing the purchase.
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training, fine-tuning, or evaluating language models, machine-learning systems, generative AI models, or similar models or systems;
embedding, prompting, querying, comparing, or otherwise enabling an AI or ML model or system to ingest, reproduce, restate, summarize, translate, reformulate, or generate outputs derived from the Product;
structured extraction, text and data mining, harvesting, or processing of the text, structure, logic, metadata, or other elements of the Product for model training, dataset creation, benchmarking, or automated knowledge extraction; or
any other activity intended to enable an AI or ML system to ingest, analyze, internalize, or generate content based on the Product.
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(b) THE EXPRESS WARRANTIES SET FORTH IN THIS SECTION 7 CONSTITUTE THE ONLY WARRANTIES WITH RESPECT TO THE PRODUCT, AND NIMONIK AND THE OWNER MAKE NO OTHER REPRESENTATION OR WARRANTY OR CONDITION OF ANY KIND, WHETHER EXPRESS OR IMPLIED (EITHER IN FACT OR BY OPERATION OF LAW), WITH RESPECT TO ANY OF THE PRODUCT, INCLUDING, WITHOUT LIMITATION, WITH RESPECT TO THE SUFFICIENCY, ACCURACY, OR UTILIZATION OF, OR ANY INFORMATION OR OPINION CONTAINED OR REFLECTED IN, ANY OF THE PRODUCT. NIMONIK AND THE OWNER EXPRESSLY DISCLAIM ALL WARRANTIES OR CONDITIONS OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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(b) If an allegation of infringement of third-party rights is made, or in Nimonik’s or the Owner’s opinion is likely to be made, with respect to any Product, Nimonik may, at its option and expense, (i) obtain for you the right to continue using the Product, (ii) modify or replace the Product so as to avoid the claim, or (iii) refund the Licence Fee. Nimonik shall have no liability if any claim would have been avoided except for your refusal to use a modified or replacement Product or to cease using the Product. This Section 9(b) states the entire liability of Nimonik and the Owner with respect to any infringement or alleged infringement of third-party rights.
(c) TO THE MAXIMUM EXTENT PERMITTED BY LAW, AND NOTWITHSTANDING ANYTHING TO THE CONTRARY IN THIS AGREEMENT, THE TOTAL AGGREGATE LIABILITY OF NIMONIK AND THE OWNER ARISING OUT OF OR IN CONNECTION WITH THIS AGREEMENT OR ANY PRODUCT SHALL NOT EXCEED THE LICENCE FEE PAID BY THE LICENSEE FOR THE PRODUCT GIVING RISE TO THE CLAIM. NOTHING IN THIS AGREEMENT EXCLUDES OR LIMITS LIABILITY THAT CANNOT BE EXCLUDED OR LIMITED UNDER APPLICABLE LAW, INCLUDING LIABILITY FOR DAMAGE CAUSED BY GROSS NEGLIGENCE OR INTENT.
This licence is granted only for the edition of the Product confirmed in Nimonik’s order confirmation and does not grant any rights to revisions or new editions of the Product. This Agreement may be terminated immediately by the Owner or Nimonik upon breach of any provision by you. Upon any expiration or termination of this Agreement, you shall immediately discontinue all use of the Product and shall, within ten (10) days, either return any hard-copy Product to Nimonik or certify in writing to Nimonik that all electronic copies of the Product (including any printed copy and any backup copy) have been permanently deleted from your devices and eliminated from your premises. Provisions that by their nature are intended to survive termination shall so survive.
You may not load, export, or re-export any of the Product, or any underlying information or technology, except in full compliance with all United States and other applicable laws and regulations.
BY ACCESSING, DOWNLOADING, PRINTING, OR OTHERWISE USING THE PRODUCT, YOU ACKNOWLEDGE THAT YOU HAVE READ THE TERMS OF THIS LICENCE AGREEMENT AND AGREE TO BE BOUND BY ITS TERMS.
This section applies to everyone who accesses or uses the Nimonik Online Store, whether or not a purchase is made. In this section, “you” means any such user.
Account. You must provide accurate and complete information when registering for an account and keep it up to date. You are responsible for keeping your account credentials confidential and for all activity that occurs under your account. Accounts are personal to a single user and may not be shared. You must notify Nimonik promptly of any unauthorized use of your account. Nimonik may suspend or terminate an account at any time for breach of these Terms or suspected misuse.
Acceptable Use. You shall not use the Nimonik Online Store in any unlawful manner; attempt to gain unauthorized access to, interfere with, or disrupt the Nimonik Online Store or its underlying systems; introduce any malware or other harmful code; or use any robot, spider, scraper, or other automated means to access, harvest, index, or copy the Nimonik Online Store or its catalogue, except for standard search-engine indexing. You shall not resell, or provide commercial access to, the Nimonik Online Store. You shall not circumvent, disable, or interfere with any security, access control, or digital rights management (DRM) or other technical protection measure applied to the Nimonik Online Store or any Product.
Website Intellectual Property. The Nimonik Online Store, including its design, layout, text, graphics, logos, and trademarks is owned by Nimonik or its licensors and is protected by applicable laws. Accessing the Nimonik Online Store grants you no rights in it other than the limited right to access and use it to browse and purchase Products. Use of the Products themselves is governed by Part B.
Website Availability. The Nimonik Online Store is provided on an “as is” and “as available” basis. Nimonik does not warrant that it will be uninterrupted, error-free, or secure, and may modify, suspend, or discontinue all or part of it at any time without notice. The disclaimers and limitations of liability in Part A, Section 7 apply equally to your access to and use of the Nimonik Online Store.
This Part D applies to Parts A, B, and C and to all access to and use of the Nimonik Online Store and the Products.
Governing Law and Dispute Resolution. These Terms are governed exclusively by the laws of the State of California, United States, without reference to its conflict of laws principles and to the exclusion of the United Nations Convention on Contracts for the International Sale of Goods. The parties consent to the exclusive jurisdiction of the state and federal courts located in California, United States. In any action to enforce these Terms, the prevailing party shall be entitled to recover its reasonable attorneys’ fees and costs.
Changes to these Terms. Nimonik may amend or update these Terms at any time by posting the revised Terms in the Nimonik Online Store. The version of these Terms in effect at the time an order is placed governs that order, and the version in effect at the time the Nimonik Online Store is used governs that use. Continued use of the Nimonik Online Store or any Product following any change constitutes acceptance of the revised Terms.
Order of Precedence. Parts A, B, and C are to be read together as a single agreement. In the event of any inconsistency concerning the use of a Product, Part B prevails; in the event of any inconsistency concerning use of the Nimonik Online Store, Part C prevails.
Customer Terms Excluded. Any terms and conditions proposed by the Licensee, whether referenced in an order or contained in any other document, are expressly excluded and shall have no effect.
No Trademark Rights. Nothing in these Terms grants the Licensee any right to use Nimonik’s or the Owner’s trademarks, logos, or other brand identifiers. Any such use requires separate written authorization, and any unauthorized use constitutes a breach of these Terms.
Electronic Communications. By using the Nimonik Online Store or placing an order, the Licensee consents to receive communications from Nimonik electronically, including invoices, notices, and other records, and agrees that such electronic communications satisfy any legal requirement that a communication be in writing.
Force Majeure. Nimonik shall not be liable for any failure or delay in performance resulting from causes beyond its reasonable control, including acts of God, natural disasters, labor disputes, carrier delays, failures of telecommunications or internet services, governmental action, or other events of force majeure.
Assignment. The Licensee may not assign or transfer these Terms, or any rights or obligations under them, without Nimonik’s prior written consent. Nimonik may freely assign these Terms. These Terms are binding upon and inure to the benefit of the parties and their permitted successors and assigns.
Waiver. No failure or delay by Nimonik in exercising any right under these Terms shall operate as a waiver of that right, and no single or partial exercise of any right shall preclude any further exercise of that or any other right.
Severability. If any provision of these Terms is held to be invalid, illegal, or unenforceable, it shall be limited or reformed only to the minimum extent necessary to make it enforceable, and the remaining provisions shall remain in full force and effect.
Entire Agreement. These Terms (Parts A, B, C, and D), together with the applicable order confirmation, constitute the entire agreement between Nimonik and the Licensee with respect to the Nimonik Online Store and the Products, and supersede all prior or contemporaneous understandings or agreements, whether written or oral. Headings are for convenience only and do not affect interpretation.
Please read these terms of service ("terms", "terms of service") carefully before using Document-Center/Nimonik website (the "service") operated by Nimonik ("us", 'we", "our").
We will provide their services to you, which are subject to the conditions stated below in this document. Every time you visit this website, use its services or make a purchase, you accept the following conditions. This is why we urge you to read them carefully.
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