UPS and critical power testing

Factory and site acceptance testing for UPS systems: full-load capacity, battery autonomy, bypass transfer and non-linear load behaviour.

Key test requirements

Full-load and overload capability verification
Battery autonomy measured to end-of-discharge voltage
Transient capture on bypass and inverter transfer
Capacitive and non-linear load conditions where required

Why battery testing needs a real load

A UPS autonomy figure assumes full load, and battery capacity falls measurably with age. The only way to obtain the real backup time is to load the UPS to rated power with a load bank and discharge the string to its end-of-discharge voltage. Estimates from the battery monitor alone are frequently far off.

Test sequence

A typical sequence: no-load start-up check; stepped loading at 25/50/75/100% with efficiency and output waveform recorded; overload capability per the specification, usually 110/125/150% for different durations; a battery discharge run after simulated mains failure; transient capture on transfers between inverter and bypass; and load-sharing accuracy on parallel systems.

Selecting the load bank

Space inside the room is limited, so rack-mounted and wall-mounted banks are the usual choice, installed near the UPS output distribution. With air-cooled units the room cooling margin has to be checked; for megawatt-class UPS systems or rooms with little spare cooling, liquid-cooled rack loads carry the heat out through the chilled-water circuit instead.

Recommended equipment

Rack-mounted Air-cooled LoadForced air-cooled load device compatible with standard 19-inch cabinets, from 2U to 6U, for power ageing verification in data centres, communication rooms and laboratories.Rack-mounted Liquid-cooled LoadHigh power-density liquid-cooled load with ≤40dB noise, solving the heat-dissipation and noise limits of air-cooled loads in the high-power segment for indoor high-density deployment.Wall-mounted Load BankProvides on-board load testing for power generation and supply equipment on special vehicles such as communication, power-supply and emergency repair vehicles, in a compact reinforced design.High-Voltage / High-Power RLC Load BankIn-house RLC load banks covering AC 400V–13.8kV up to 10,000kW for performance and steady-state aging testing of gensets, UPS, PV inverters and storage PCS.Load Testing SystemComputer-based test system with a PLC control core and high-speed data acquisition for steady-state, transient, continuous-operation and harmonic testing of generator sets.

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Other applications

Data centre and computing centre power testing Marine power system testing Diesel and gas genset load testing PV and battery storage system testing