A UPS is a product whose entire purpose is to be trusted in a failure, so its certification evidence has to prove behaviour under exactly the conditions the product is sold to handle. Paper C stacks that evidence for a nickel-metal hydride bridge source: the IEC 62040 series that governs UPS safety, performance classification and DC systems, the ride-through and recharge verifications that demonstrate the bridge, and the cell-level IEC 61951-2, IEC 62133-1 and UN 38.3 documents that establish performance, safety and shippability. The result is a coherent file a UPS or instrument manufacturer can place directly behind its declaration.
The UPS evidence begins with IEC 62040-1, the safety standard for uninterruptible power systems, which governs electrical, thermal and mechanical safety of the finished equipment, including the battery compartment, insulation and protection against fault. The battery does not carry the equipment-level certificate itself, but its construction and protection must be compatible with it: fusing, insulation, creepage and the behaviour under a battery fault all flow from the cell and pack design. Choosing a chemistry with an intrinsically forgiving aqueous failure mode - NiMH rather than a lithium chemistry requiring an electronic safety layer - simplifies the equipment safety case.
Beneath the safety standard sits the performance frame, and the supplier's cell evidence must be specified in the same language the UPS standard uses so the two layers connect cleanly in the technical file.
IEC 62040-3 is where the product's VFD, VI or VFI classification - and its environmental and performance classes - is established through defined tests of normal-operation output, transfer behaviour and dynamic performance. The battery enters this layer through the discharge and recharge tests that demonstrate the claimed autonomy and the output's behaviour during transfer and bridge: the load is applied as it would be in a real outage, the transfer break and output voltage envelope are measured against the claimed class, and the bridge is run to the rated time. IEC 62040-5 provides the analogous frame for DC UPS backing a DC bus directly.
For the NiMH supplier this means providing delivered-voltage curves at the actual bridge current - not merely a reference-capacity figure - so the UPS designer can predict that the DC rail stays inside the inverter's input window for the whole rated bridge, including the step-load instant.
Three practical tests close the performance loop. The ride-through test applies a representative outage with the full protected load, including inrush, and verifies the bridge completes the rated shutdown or generator-span with the rail in tolerance. The recharge test verifies the pack recovers its bridge capability within the claimed time after an event - important in outage-prone grids. The repeat-cycle test runs many outage/recharge cycles and confirms the bridge still completes late in life, guarding against the optimistic day-one rating.
The animated fade curve illustrates the quantity these tests police: usable capacity declines with cycles and faster in a hot cabinet, and the rated bridge must remain achievable on the faded pack. This is precisely why Paper B applies rate, temperature and end-of-life derating; the certification tests confirm the margin was real.
IEC 61951-2 supplies the standardised cell-performance methods for sealed NiMH: the reference charge and discharge, the 20-degree capacity test, charge retention after storage, the endurance regime of at least 500 cycles, overcharge and long-term charge behaviour. These give the UPS manufacturer a defensible, test-house-recognised basis for the pack's capacity and life claims rather than bespoke supplier numbers. For a high-rate bridge source, the most useful additions are discharge curves at elevated currents and across temperature, which translate the reference capacity into the specific ride-through envelope.
Because a UPS stands ready for long periods, charge-retention and long-term-charge data are as relevant as cycle life: they show the pack will still hold its bridge after months of readiness under the maintenance charger.
Sealed-nickel safety is established by IEC 62133-1, covering continuous low-rate charging, external short circuit, forced discharge and the mechanical and thermal abuse cases appropriate to the chemistry; NiMH's venting, non-propagating failure behaviour keeps the pack-level protection straightforward. For transport, sealed NiMH travels under the UN 38.3 test-summary regime but, unlike lithium, is not subject to lithium-battery restrictions under IATA/ICAO and ADR - a meaningful logistics advantage for UPS products shipped in small numbers, and for replacement packs dispatched urgently to site.
Providing the UN 38.3 summary and a nickel-chemistry declaration alongside the safety report means the finished UPS and its spares move through freight without the labelling, state-of-charge and quantity constraints that complicate lithium backups.
Ordered top to bottom, the evidence forms a closed chain: IEC 62040-1 frames equipment safety; IEC 62040-3 (and 62040-5 for DC) establish and test the VFD/VI/VFI performance claim and the bridge; ride-through, recharge and repeat-cycle tests prove the rated autonomy over life; IEC 61951-2 characterises the cell's capacity, endurance and retention; IEC 62133-1 proves its abuse safety; and UN 38.3 with the chemistry declaration clears shipping. A NiMH supplier that delivers matched-lot pack records and high-rate, wide-temperature discharge curves against this stack lets the UPS manufacturer declare its class and autonomy with predictable, repeatable evidence.
Papers A through C together cover the duty, the sizing and the certification of nickel-metal hydride in small-UPS and instrument backup - the complete case for a bridge source that is ready for years and decisive for the seconds that matter.
Weijiang Power supplies certified high-rate NiMH packs for small-UPS and DC-UPS manufacturers: IEC 61951-2 capacity, endurance and charge-retention reports, high-rate and wide-temperature discharge curves for bridge prediction, IEC 62133-1 sealed-nickel safety evidence, UN 38.3 summaries and nickel-chemistry shipping declarations. Send your IEC 62040-3 target class, protected load and bridge time and we will assemble the cell evidence your technical file needs.
