Defence and marine engineering terms

An 11 kV substation steps down electricity at 11,000 volts through transformers for distribution within a building or facility. Maintenance schedules for its transformers cover hourly load and temperature checks in attended substations, periodic checks of oil condition, bushings and gaskets, and yearly tests of insulation and earth resistance.

Source IS 10028 (Part 3):1981, Code of practice for maintenance of transformers, Bureau of Indian Standards

See AMC and building operation and maintenance, 11 kV substation transformer maintenance schedule

A 400 Hz supply is an AC power source at 400 hertz, well above the 50 or 60 Hz used for general shore supply. It feeds aircraft systems and much naval radar, weapon, communication and navigation equipment, because a higher frequency lets transformers and power supplies be made smaller and lighter.

Source Frequency changer, Wikipedia

See Rotary frequency converter, Why navies use 400 Hz power

A battery charging rectifier converts an AC supply to DC to charge and maintain a lead-acid battery bank while also supplying a connected DC load. It typically operates in float mode for continuous standby charging and switches to boost mode to recharge the battery faster after a discharge.

Source The proper charging of stationary lead-acid batteries, Vertiv, presented at BATTCON 2010

See Battery charging rectifier, What does a battery charging rectifier do

Boost, or equalize, charging raises a lead-acid battery's charging voltage above its normal float level for a limited time, to recharge a discharged battery faster or to even out cell voltages and electrolyte specific gravity across a string. It increases gassing and water loss, so duration and voltage follow the battery maker's limits.

Source The proper charging of stationary lead-acid batteries, Vertiv, presented at BATTCON 2010

See Battery charging rectifier, Float vs boost charging for naval batteries

A classification society is an independent organisation that sets technical rules for the design, construction and survey of ships and marine equipment, and issues certificates confirming compliance. Its surveyors carry out periodic surveys, including type approval of equipment and inspections during dry docking, and many societies work together through IACS on common Unified Requirements.

Source Type Approval Procedure, Indian Register of Shipping

See Hull maintenance service, Shafting service, Dry docking intervals and extended dry docking under IRS

A comprehensive maintenance contract includes spare parts and most repairs within a fixed annual fee, alongside scheduled preventive maintenance, in contrast to a non-comprehensive contract where parts are billed separately. It costs more but caps unexpected repair bills, so the contract's exclusions list needs careful reading before signing.

Source Comprehensive vs non-comprehensive AMC, Heaven Green Energy

See AMC and building operation and maintenance, Comprehensive vs non-comprehensive building O&M contracts

The Central Public Procurement Portal, run by the National Informatics Centre, is where central ministries, departments and public sector undertakings publish tenders and, for many, conduct e-procurement. Bidders enrol on it with a valid digital signature certificate before submitting bids for advertised tenders.

Source CPPP guidelines, National Informatics Centre

See Vendor registration, Defence tender portals: CPPP and Defproc

DAP 2020 governs capital acquisition of equipment, platforms and systems for India's armed forces. It gives priority to the Buy (Indian-IDDM) category, meaning equipment indigenously designed, developed and manufactured with a minimum indigenous content, and it remains the governing procedure while a revised edition is under preparation.

Source PIB press release, PRID 2226097, Press Information Bureau, Ministry of Defence

See DAP 2020 procurement categories explained

A DG set is a diesel engine coupled to an electrical generator, used as a standby or backup power source when the mains supply fails. Maintenance follows the engine maker's schedule by running hours and calendar time, and a standby set is normally exercised on load at least once a month to keep it reliable.

Source Power Topic 7004: Maintenance is one key to diesel generator set reliability, Cummins Power Generation

See AMC and building operation and maintenance, DG set maintenance schedule in India

DGAQA works under the Department of Defence Production and is the authority for quality assurance and final acceptance of military aircraft, aero engines, airborne systems, avionics and allied ground systems. It oversees production, repair and overhaul work at defence public sector undertakings and private firms, and registers firms supplying aviation stores.

Source About Us, Directorate General of Aeronautical Quality Assurance

See Quality assurance, DGQA and DGAQA vendor registration explained

DGQA is the Ministry of Defence organisation responsible for the quality of defence stores bought for the armed forces. Its technical directorates, such as DQA(N) for naval items, approve quality assurance plans, inspect production, run factory acceptance trials and accept stores, and the organisation also registers and assesses supplier firms.

Source DGQA, Directorate General of Quality Assurance, Ministry of Defence

See Quality assurance, Vendor registration, DGQA and DGAQA vendor registration explained

DPM 2025 is the Ministry of Defence manual governing revenue procurement, meaning maintenance, sustenance, spares, repairs and services bought by the three Services and other Ministry of Defence establishments. Released in October 2025 and effective from 1 November 2025, it replaced DPM 2009 and added chapters on indigenisation and ICT procurement.

Source PIB press release, PRID 2181894, Press Information Bureau, Ministry of Defence

See Marine engineering division, DPM 2025 key changes

A DPSU is a public sector company under India's Ministry of Defence engaged in defence production. Long standing DPSUs include Hindustan Aeronautics, Bharat Electronics, Bharat Dynamics and the shipbuilding yards, and seven more were created in 2021 when the Ordnance Factory Board was corporatised.

Source PIB press release, PRID 2033571, Press Information Bureau, Ministry of Defence

See Vendor registration, Marine engineering division, Shipyard and DPSU vendor registration

DQA(N) is a technical directorate of the Directorate General of Quality Assurance under India's Ministry of Defence. It provides quality assurance for electrical, electronics and weapon equipment and naval stores bought by the Navy, the Coast Guard and shipyards, approving quality assurance plans and conducting factory acceptance trials.

Source DQA(N), Directorate General of Quality Assurance, Ministry of Defence

See Quality assurance, Battery charging rectifier, DQA(N) type approval certificate explained

Earnest money deposit, also called bid security, is money a bidder deposits with a tender to show it is a serious bid. It is forfeited if the bidder withdraws or fails to sign the resulting contract, and under government financial rules it commonly ranges from about 2 to 5 percent of the estimated value. Registered micro and small enterprises are usually exempt.

Source General Financial Rules 2017 (CPPP compilation), Rule 170, Department of Public Enterprises

See Vendor registration, EMD and performance bank guarantee rules

A Factory Acceptance Trial is testing carried out at a manufacturer's works, before despatch, to demonstrate that equipment meets its specification. For naval stores, inspection and factory acceptance trials are run as per the approved quality assurance plan, which decides which tests are performed and witnessed.

Source DQA(WP), Directorate General of Quality Assurance, Ministry of Defence

See Quality assurance, QAP, FAT and ATP in defence supply explained

First article inspection is a documented check confirming that a new or changed production process makes a part meeting every drawing and specification requirement. A representative first production unit is fully measured, and its materials, special processes and tests are verified, before series production is allowed to continue.

Source First article inspection, Wikipedia

See Quality assurance, Indigenisation service, QAP, FAT and ATP in defence supply explained

Float charging holds a fully charged lead-acid battery at a constant voltage just above its open-circuit voltage, replacing the energy lost to self-discharge while the charger also supplies the connected load. The correct float voltage depends on the battery's design and must be adjusted for temperature.

Source The proper charging of stationary lead-acid batteries, Vertiv, presented at BATTCON 2010

See Battery charging rectifier, Float vs boost charging for naval batteries

GeM is the online marketplace through which Indian government buyers purchase goods and services. Central government procuring entities are required to buy goods and services available on it, and both buyers and sellers, including MSMEs, register on the platform to take part in tenders and direct purchases.

Source General Financial Rules 2017 (CPPP compilation), Rule 149, Department of Public Enterprises

See Vendor registration, GeM for defence suppliers

IACS is the association of classification societies that publishes Unified Requirements setting common minimum technical standards for ship design, construction and survey. Its Unified Requirement Z21, for example, sets the survey scope and intervals for propeller shafts and tube shafts on merchant ships worldwide.

Source IACS UR Z21, Rev.4 2015, Surveys of Propeller Shafts and Tube Shafts, International Association of Classification Societies

See Shafting service, Propeller shaft survey intervals under IACS UR Z21

IDDM describes equipment designed, developed and manufactured within India. Buy (Indian-IDDM) is the most preferred capital procurement category under the Defence Acquisition Procedure, requiring a minimum share of indigenous content, used to give Indian-origin designs priority over imported or licence-built alternatives.

Source PIB press release, PRID 2226097, Press Information Bureau, Ministry of Defence

See Indigenisation, DAP 2020 procurement categories explained

iDEX is the operational framework of the Defence Innovation Organisation, set up to fund and adopt defence innovation from startups, MSMEs and individual innovators. Winners of its challenges, such as the Defence India Startup Challenge and ADITI, sign a grant agreement and build prototypes for the armed forces and other defence agencies.

Source iDEX FAQ, Innovations for Defence Excellence

See Indigenisation, iDEX, DISC and ADITI funding for startups and MSMEs

Indigenisation means replacing an imported defence item, from a whole system down to a spare or raw material, with one designed or made in India. It is pursued through Positive Indigenisation Lists, the SRIJAN portal, Make procedures and innovation schemes, so that items are bought from Indian industry once development succeeds.

Source PIB press release, PRID 2300723, Press Information Bureau, Ministry of Defence

See Indigenisation, Indigenisation service, Indigenising a naval spare, from sample to approval

An industrial licence permits manufacture of specified defence items under the Industries (Development and Regulation) Act, required only for items listed by the Department of Defence Production. It is valid for 15 years, extendable by 3 more years, and is granted only to Indian-incorporated entities, not to foreign companies directly.

Source Press Note 1 (2019 Series), Department for Promotion of Industry and Internal Trade

See Defence division, Defence industrial licence under the IDR Act and Arms Rules

ISO 9001:2015 is the international standard for quality management systems, setting requirements for how an organisation plans, controls and improves its processes to consistently meet customer and regulatory requirements. It is a common baseline expected of registered defence vendors and a condition for schemes such as self-certification of supplies.

Source Self-Certification Status, Directorate General of Quality Assurance, Ministry of Defence

See Quality assurance, Vendor registration

A Joint Services Specification is a standard published by the Directorate of Standardisation under the Department of Defence Production for use across the Indian armed forces, alongside Joint Services Guides. JSS 55555, on environmental test methods for electronic and electrical equipment, is a widely used example.

Source SOP for Vendors Registration, Directorate of Standardisation, Department of Defence Production

See Quality assurance, JSS 55555 environmental tests explained

JSS 55555 is India's Joint Services Specification of environmental test methods for electronic and electrical equipment used by the armed forces. It sets standard tests, such as heat, cold, humidity, salt, mould, dust, vibration and shock, used to demonstrate that equipment can survive its service conditions during type testing.

Source Guidelines for Environmental Testing at CQAE (WE), Bangalore, DQA(N), Ministry of Defence

See Quality assurance, JSS 55555 environmental tests explained

L1 is the lowest priced bid among bidders found technically qualified in a government tender, with L2 the next lowest and so on. Contracts normally go to L1, subject to rules such as purchase preference for local suppliers and price matching rights for micro and small enterprises within a set margin above L1.

Source Public Procurement (Preference to Make in India) Order, Department for Promotion of Industry and Internal Trade

See Vendor registration, L1 evaluation and reverse auctions

Make II is a route under India's Defence Acquisition Procedure for developing equipment where industry funds prototype development itself, with no government funding, typically to substitute imports or field an innovative solution. It differs from Make I, where the government funds part of prototype development.

Source PIB press release, PRID 1802587, Press Information Bureau, Ministry of Defence

See Indigenisation, Indigenisation service, Make II procedure basics

A motor-generator set couples an electric motor to a generator to convert electrical power from one form to another, such as one frequency to another, AC to DC, or one voltage to another. Its rotating mass also isolates the load from supply disturbances and can ride through brief interruptions or switching transients.

Source Motor-generator, Wikipedia

See Rotary frequency converter, What is a motor-generator set

MSME is the classification, based on investment in plant and machinery and annual turnover, used for micro, small and medium enterprises in India. MSMEs registered under Udyam get benefits in public procurement, such as exemption from earnest money deposit, free tender documents and price matching rights against the lowest bid.

Source FAQs on the Public Procurement Policy for MSEs, Development Commissioner (MSME), Ministry of MSME

See Vendor registration, MSME benefits in public procurement

NSS is the Indian Naval Shock Standard, applied together with the UK shock manual BR 3021. NSS Grade I, or curve A, covers equipment that affects a ship's combat efficiency and must keep working after underwater shock. NSS Grade II, or curve B, covers equipment that does not affect fighting capability.

Source Guidelines on Shock Standards and Shock Testing of Naval Electronic/Electrical Equipment, Directorate General of Quality Assurance, Ministry of Defence

See Quality assurance, Shock testing of naval equipment and NSS shock grades

A performance bank guarantee is a bank's undertaking, submitted by a contract winner, covering a percentage of the contract value in case of non-performance. Under government financial rules it is commonly set between about 3 and 10 percent of contract value, with the exact figure and acceptable forms stated in the tender document.

Source Circular on performance security, Rule 171, Department of Expenditure, Ministry of Finance

See Vendor registration, EMD and performance bank guarantee rules

A Positive Indigenisation List is a Ministry of Defence notification of items that, after an indicated timeline, will be procured only from Indian industry rather than imported. Department of Military Affairs lists cover systems and platforms for the Services, while Department of Defence Production lists cover sub-systems, spares, components and raw materials for defence public sector undertakings.

Source PIB press release, PRID 2033571, Press Information Bureau, Ministry of Defence

See Indigenisation, Positive Indigenisation Lists explained

A Quality Assurance Plan lists every inspection and test stage for an item, including the characteristic checked, the method used, the acceptance criteria, records kept and who witnesses each stage. For naval stores it is approved by the inspecting quality assurance authority, which then inspects and runs factory acceptance trials against it.

Source DQA(N), Directorate General of Quality Assurance, Ministry of Defence

See Quality assurance, QAP, FAT and ATP in defence supply explained

A rotary frequency converter is a motor-generator set in which an electric motor, fed from the available supply, drives a generator on a common shaft. Because the generator's output frequency depends on its speed and winding, it converts a 50 or 60 Hz supply into another frequency, such as 400 Hz, for equipment that needs it.

Source Frequency changer, Wikipedia

See Rotary frequency converter, Rotary vs static frequency converter

SCOMET is India's list of items whose export is controlled for strategic and security reasons. Category 6 of the list covers munitions, and export authorisation for these items is issued by the Department of Defence Production, while other SCOMET categories are handled by the Directorate General of Foreign Trade.

Source PIB press release, PRID 1884818, Press Information Bureau, Ministry of Defence

See Defence division, Defence exports authorisation and SCOMET basics

SRIJAN is the Department of Defence Production's indigenisation portal, where defence public sector undertakings and Service Headquarters offer items to Indian industry, including MSMEs and startups, for indigenous development and production. Firms respond to Expressions of Interest or RFPs linked from the portal's public dashboard.

Source PIB press release, PRID 2300723, Press Information Bureau, Ministry of Defence

See Indigenisation, Indigenisation service, The SRIJAN portal for defence vendors

A Type Approval Certificate confirms that a product's design has been evaluated, usually through drawing review and type tests on a prototype, and found to meet stated requirements. The approval applies to later production units of the identical design, which are still inspected individually, and validity and scope are recorded on the certificate itself.

Source Type Approval Procedure, Indian Register of Shipping

See Quality assurance, Battery charging rectifier, DQA(N) type approval certificate explained

The Technology Development Fund is a Ministry of Defence scheme, run by DRDO, that funds indigenous development of components, products, systems and technologies by MSMEs and startups. It covers a large share of project cost, allows consortia with industry or academia, and funds projects up to a stated ceiling per project.

Source PIB press release, PRID 1832042, Press Information Bureau, Ministry of Defence

See Indigenisation, Technology Development Fund (TDF) explained

Udyam is the Government of India's free, paperless, self-declaration based registration system for micro, small and medium enterprises. Registration on Udyam is required for an MSME to claim public procurement benefits such as earnest money exemption and price matching rights, and no fee is payable to anyone for registering.

Source Udyam Registration, Ministry of Micro, Small and Medium Enterprises

See Vendor registration, Udyam registration and defence suppliers