/ RESERVE POWER · APPLICATION
Substation battery — the DC heart of switchgear and protection
When the grid fails, everything in a substation that still works — trip coils, protection relays, breaker charging, SCADA, emergency lighting — works because of one battery bank. This page explains that duty and how to specify for it. Microtex supplies substation batteries built on flooded tubular OPzS cells, seismically qualified and type-tested at CPRI.
Seismically qualified — IEEE 344 · CPRI · NPCIL-witnessed — Approved vendor: NPCIL · BARC · Indian oil companies — 110 / 220 V DC banks
The duty: years of silence, then one violent minute
A substation battery floats quietly across its DC bus for years — and is judged entirely by a few emergency minutes: breaker trip pulses of high current, then hours of control and communication load until supply returns. The specification that survives this is not “capacity” alone but the whole voltage window: the bank must hold the DC bus above the protection scheme’s minimum voltage at the end of the autonomy period, at the room’s real temperature, at the end of the battery’s life — not the beginning.
That end-of-life honesty is why utilities specify flooded tubular OPzS for this duty: the technology whose condition can be checked cell by cell — voltage, impedance trend, specific gravity — and whose capacity can be proven outright by discharge test, whose life is the longest of any lead-acid construction, and whose behaviour after twenty years is documented rather than guessed. The construction is explained on our technology page.
What to put in the specification
Tender engineers: these seven lines decide whether the bank you receive matches the bank you imagined. State them explicitly and demand evidence against each.
| DC system voltage window | Nominal bus voltage and the permitted maximum/minimum — this fixes the cell count and end-of-discharge voltage |
| Duty cycle | Momentary loads (trip coils, breaker motors) and continuous loads (relays, SCADA, lighting), with durations |
| Autonomy | Hours the bank must carry the load with charger failed — per your utility’s planning standard |
| Ambient | Real battery-room temperature range — life and capacity both move with it |
| Ageing margin | Design margin so the bank still meets duty at end of life |
| Seismic requirement | Where applicable: qualification per IEEE Std 344 — our 2V OPzS cells carry this, tested at CPRI, witnessed by NPCIL QA* |
| Evidence | Type-test reports with ULR numbers, vendor registrations, FAT with witness — all quoted in our tender documentation |
* TYPE TEST HELD BY MYSORE THERMO ELECTRIC PVT LTD, A MICROTEX GROUP COMPANY.
Questions substation engineers ask us
How many cells for a 110 V or 220 V DC system?
The cell count follows from your voltage window, not from habit: the bank’s float voltage must sit inside the bus maximum, and the end-of-discharge voltage across all cells must stay above the bus minimum. Give us both limits and the count falls out — we size to your window and show the arithmetic in the proposal.
Flooded OPzS or sealed VRLA for a substation?
Utilities with trained maintenance overwhelmingly specify flooded OPzS: longest verifiable life, cell-by-cell inspection, and decades of documented grid service. Sealed types suit unmanned kiosks and compact rooms — the trade-offs are on the OPzS and OPzV Gel pages.
What proves a battery is fit for a seismic-zone substation?
A type test on the shake table, not a paragraph in a brochure: Resonance Search, OBE and SSE testing per IEEE Std 344:2013. Our 2V OPzS cells carry exactly that qualification, tested at CPRI Bengaluru and witnessed by NPCIL QA — report and ULR numbers travel with our tenders.
Can you support vendor registration and tender documentation?
Yes — approved-vendor registrations with NPCIL, BARC and Indian oil companies are held, and our tender packs carry type-test reports, manuals, drawings and FAT protocols. Send the annexures with your enquiry and we return the compliance statement with the quotation.
What maintenance does a substation bank actually need?
Less than folklore says, more than neglect allows: hold the float voltage, keep the room ventilated and near design temperature, water with clean water on schedule, and record cell voltages and SG on a round. The discipline is simple; skipping it is what shortens bank life — our manuals set out the full round.