Find the family.
Then the exact fit.

1–1,200 kV; exact capacitance, current, flange and conductor interface; OIP/RIP/RIS/porcelain/composite

Contact sets, diverter inserts, vacuum interrupters, gears and seals; exact OLTC type/revision required

Fans, pumps, radiators, valves, thermostats and controllers from small distribution to 1,300 MVA units

Small alternator through multi-hundred-MVA turbogenerator; exact frame, poles, excitation and balance data

Small genset through multi-hundred-MVA machine; core/winding/frame dimensions unique

Legacy and current genset controllers; 12/24 Vdc; exact firmware, harness and engine interface

Compressor and hot-gas-path blades from microturbine to large frame; stage/alloy/coating/serial-specific

Journal/thrust/rolling bearings; exact shaft size, load, oil and machine serial

Spring/hydraulic/pneumatic mechanisms; LV/MV/HV; exact breaker type and stored-energy duty

MCCB/ACB electronic or thermal-magnetic units; frame, sensor plug, firmware and protection functions

Electromechanical and numerical relays; exact case, CT/VT, supply, firmware and protocol options

CPU, I/O, communication and power modules; exact family/revision/firmware; new/surplus/refurbished

Panel/display/keypad/touch/communication modules; exact model, screen and firmware

Rectifier, IGBT, gate driver, capacitor and control boards; exact drive frame/voltage/revision

Rectifier/inverter/static switch/bypass modules; exact kW, DC bus, firmware and cabinet

Power stack, IGBT/SiC module, control board, filter and cooling module; exact PCS family

2–30 kWh common; exact chemistry, voltage, BMS protocol, mechanical interface and ageing match

Any obsolete PLC/HMI/drive/relay/control board; part number, revision and firmware define the item