In short. Every DG set should have one file, paper and scanned, holding six groups of records: identity and purchase, compliance certificates, installation approvals, commissioning tests, operation and maintenance history, and changes and incidents. A complete file speeds up inspections, warranty claims and insurance claims, settles disputes with service providers, and makes the set easier to value when it is sold, exchanged or relocated. The printable checklist on this page lists every document and tells you who issues it and how long to keep it.
Who this page is for: owners, facility and maintenance managers, apartment association committees taking over from a builder, auditors, and anyone buying or selling a used set.
Key facts
- Which authority governs which approval, and how to keep a dated compliance record, is explained on our regulatory updates page. This page is the physical file itself: what goes in it, who issues each item, how long to keep it and how to organise it.
- The single most useful record is the engine serial number. Parts identification, warranty and emission certificates all trace back to it.
- Keep identity, compliance and approval documents for the life of the set. Keep maintenance records for the life of the set as well; they are what a buyer, an insurer or an investigator looks at.
- A load-bank test report is the only objective proof of what the set can deliver. Repeat it after major repairs and at least once in every few years of light-load standby service.
Why the file matters more than most owners think
Generators fail on the day they are needed most. When they do, the questions arrive at once. Was it serviced? With what oil and which filters? When was the last load test? Who changed the controller settings? A maintenance team with a complete file answers in minutes. One without it argues for weeks.
The file also has a direct effect on value. A used set with a clear history — original invoice, serial numbers that match the certificates, a service log and a recent load-bank report — can be inspected, priced and transferred with confidence. A set with no papers is valued on condition alone, after a longer inspection, and buyers rightly allow for the unknowns.
Finally, the file protects people. A record of earth resistance tests, protection checks and changeover interlock checks is evidence that the installation was safe on the day something went wrong elsewhere.
The six sections of a complete DG set file
A. Identity and purchase
- Tax invoice and delivery note, showing the model, kVA rating, engine serial, alternator serial and panel serial
- Photographs of every nameplate: engine, alternator, controller, panel and enclosure
- Warranty card or certificate, with start date and terms
- Manufacturer’s operation and maintenance manuals, parts catalogue and wiring diagrams
- For used or refurbished sets: the seller’s inspection report, refurbishment scope and warranty terms
B. Compliance certificates
- Engine emission type approval and conformity of production certificate references, matching the engine serial
- Noise type approval reference and a photograph of the enclosure conformance label
- Test certificate of the set from the factory: load test, insulation and voltage regulation
- For dual-fuel conversions or retrofit emission devices: the conversion or device documents
C. Installation and approvals
- Single-line diagram as built, showing the generator, breaker, changeover, ATS or AMF and cable sizes
- Earthing layout with pit locations and conductor sizes
- Electrical Inspectorate approval or self-certification record before energisation, and every periodic inspection report since
- Pollution-board consent entry, or a note of the exemption basis
- Exhaust stack height calculation and the as-built height
- Fire NOC references covering the DG room and fuel storage, where applicable
- Licensed contractor’s completion certificate and test report
D. Commissioning and test records
- Commissioning report: no-load and load readings, voltage and frequency regulation, protection trips
- Insulation resistance of alternator windings and cables, with test voltage and temperature
- Earth resistance of each pit, with instrument and method
- Load-bank test reports, from first commissioning and from every later test
- Controller configuration printout or saved file, with the protection setpoints
E. Operation and maintenance history
- The log book: daily checks, running hours, fuel added and alarms
- Service reports by hour meter, listing parts and fluids used
- AMC agreement and visit records
- Oil and coolant analysis reports, if taken
- Battery replacement records, and fuel cleaning or tank inspection records
F. Changes and incidents
- Every modification — new panel, ATS, controller change, rewinding, overhaul — with date, scope and the person responsible
- Breakdown and repair reports with root cause
- Relocation records, and the fresh approvals they triggered
- Any safety incident, near miss or complaint, with the corrective action taken
Who issues what, and how long to keep it
| Document | Issued by | When you get it | Keep for | Why it matters |
|---|---|---|---|---|
| Invoice and delivery note with serials | Supplier | At delivery | Life of set, then pass to the buyer | Proof of ownership; links all serials |
| Nameplate photographs | You | At delivery | Life of set | Plates fade, corrode and get painted over |
| Emission and noise approval references and labels | Manufacturer | At delivery | Life of set | Lawful sale and use; inspections |
| Factory test certificate | Manufacturer | At delivery | Life of set | Baseline for every later test |
| Single-line diagram and earthing layout | Designer or contractor | Before installation; updated as built | Life of set; revise after changes | Inspectorate approval and safe isolation |
| Inspectorate approval or self-certification | Inspectorate or owner | Before energisation | Life of set | Legal energisation; insurance |
| Periodic inspection reports | Inspectorate or owner | At the interval the state sets, never more than five years | Life of set | Continuing compliance |
| Commissioning and load-bank reports | Service engineer | At commissioning; after major work | Life of set | Proof of real capacity |
| Log book and service reports | Operator and service engineer | Daily and per service | Life of set | Warranty, resale, root cause |
| Modification and repair reports | Service provider | After each event | Life of set | Explains today’s configuration |
How to organise it so it stays useful
- One file per set, not per site. Two sets at one site need two files, because serials, hours and histories differ.
- Paper and scan. Keep a ring binder in the site office, not in the DG room where heat and oil ruin paper, and a scanned copy in a shared folder.
- Name scans so they sort themselves. Use site, set number, section, document and date: for example FactoryA-DG1-C-InspectorateApproval-2026-03-14.
- A cover sheet on top, listing the set’s identity, hours at the last service, the date of the next periodic inspection and who holds the AMC.
- Review twice a year. Tick the checklist below, list the gaps and assign someone to close each one.
DG set document file checklist
| Site | Set no. | kVA | Engine serial | Alternator serial | Reviewed by / date |
|---|---|---|---|---|---|
| Section | Document | Held (✓/✗) | Date / reference | Action if missing |
|---|---|---|---|---|
| A | Invoice and delivery note with all serials | |||
| A | Nameplate photographs (engine, alternator, controller, panel, enclosure) | |||
| A | Warranty certificate and terms | |||
| A | O&M manuals, parts catalogue, wiring diagrams | |||
| B | Emission approval and COP references matching engine serial | |||
| B | Noise approval reference and label photograph | |||
| B | Factory test certificate | |||
| C | As-built single-line diagram | |||
| C | Earthing layout and pit list | |||
| C | Inspectorate approval or self-certification | |||
| C | Latest periodic inspection report (within 5 years) | |||
| C | Pollution-board consent entry or exemption note | |||
| C | Stack height calculation and as-built height | |||
| C | Fire NOC reference (if applicable) | |||
| C | Contractor completion certificate and licence copy | |||
| D | Commissioning report | |||
| D | Insulation resistance records | |||
| D | Earth resistance records (each pit) | |||
| D | Latest load-bank test report | |||
| D | Controller settings printout or file | |||
| E | Log book (current and archived) | |||
| E | Service reports by hour meter | |||
| E | AMC agreement and visit records | |||
| E | Battery, fuel-tank and fuel-cleaning records | |||
| F | Modification records (panel, ATS, controller, rewind, overhaul) | |||
| F | Breakdown reports with root cause | |||
| F | Relocation records and fresh approvals | |||
| F | Incident, near-miss and complaint records |
Worked example (illustrative): rebuilding the file of a 12-year-old 160 kVA hospital set
The situation. A 60-bed hospital took over a 160 kVA set from the previous management. The only papers were a few service bills. An upcoming periodic inspection and an insurance renewal both asked for records.
- Identity recovered. The engine and alternator plates were cleaned and photographed. The engine serial let the manufacturer’s dealer network confirm the model and build year. The build year showed the emission stage of the time, which went into the file as a note.
- Drawings recreated. Our service engineers traced the circuit from alternator to changeover to main panel, and drew an as-built single-line diagram. They found the changeover was a manual switch with no mechanical interlock, and replaced it with an interlocked unit before anything else.
- Tests re-established. Alternator insulation resistance was tested and recorded with the test voltage and temperature. Each earth pit was tested; one read well above the design value, so it was rebuilt and retested.
- Capacity proven. A load-bank test at 25%, 50%, 75% and 100% load for 30 minutes per step recorded voltage, frequency, coolant temperature and oil pressure. At full load, coolant temperature settled within the normal band, so the radiator was confirmed adequate.
- History started. A log book was opened at the current hour-meter reading, and the next service was set by hours.
Result: sections A, C, D and E were complete within three weeks. Section B was completed as far as records allowed, with a clear note of what could not be recovered. The inspection and the insurance renewal went ahead on documented facts.
Exceptions and cautions
- A missing original certificate cannot be recreated by anyone other than its issuer. Record what is missing and why; never fill the gap with an invented reference.
- Controller settings saved on a laptop are lost when the laptop is lost. Print them and file the print.
- For rented sets, the rental company holds sections A and B. You keep a copy of the set’s identity and test records for the hire period, plus your own connection and earthing records.
- When a set is sold or exchanged, hand over sections A, B, D and E with it. Section C belongs to the site, because the approvals are for the installation, not the machine.
Common mistakes
- Keeping the file in the DG room, where heat, oil and damp destroy it.
- Service bills with no hour-meter reading, so nobody knows when the work was done in engine terms.
- Single-line diagrams drawn at handover and never updated after an ATS or panel change.
- Earth resistance noted as “OK” without a value, instrument or date.
- No load-bank record at all, so the first real full-load run happens during an outage.
- Discarding the old set’s file at replacement, when it is needed to sell or exchange the old set.
What to send us
Send photographs of the nameplates and whatever papers you have. Our service engineers will tell you which sections are complete, which can be rebuilt by inspection and testing, and which can only be recorded as unavailable. We can carry out the tests that fill the gaps: insulation, earth resistance, protection checks and load-bank testing. Use the service enquiry, or WhatsApp 98852 01608. We work across Telangana, Andhra Pradesh and every district within about 300 km of Hyderabad, with project support across India.
Questions engineers ask
What documents should come with a new generator?
The invoice with engine, alternator and panel serials, the warranty, the operation and maintenance manuals, the factory test certificate, and the emission and noise approval references, with labels on the set that match them.
How long should I keep generator service records?
For the life of the set. Service and test history is what a buyer, an insurer, an inspector or a failure investigator relies on, and it should pass to the next owner with the set.
What if the original certificates are lost?
Ask the issuer for a copy, using the serial numbers. If a copy cannot be obtained, record what is missing and why. Never fill the gap with an invented or borrowed reference.
Which records go with the set when I sell it?
Identity and purchase records, compliance certificates, test reports and the maintenance history. Installation approvals stay with the site, because they relate to the installation, not the machine.
Why is a load-bank report so important?
It is the only objective proof of what the set can deliver at its rated load. A standby set that never sees full load in normal service can hide cooling, fuel or governor problems until a real outage.
Should the DG file be kept in the generator room?
No. Keep the working log book near the set, but keep the master file in the site office and a scanned copy in a shared folder, safe from heat, oil and damp.
Related pages
- DG set log book: daily, weekly and monthly entries
- DG set approvals in Telangana and Andhra Pradesh
- Generator noise limits in India
- India genset emission norms
- Load-bank testing
- Used generator inspection
- Used generator prices
Technical content reviewed by D. Srinivas Reddy, Managing Partner and service engineer. Last updated 5 November 2026.