Doble

Doble

Doble Engineering Company is a specialist manufacturer of diagnostic and testing instruments for high-voltage electrical equipment. Founded in 1920 and headquartered in Watertown, Massachusetts, Doble has over a century of expertise serving electric utilities, independent power producers, and industrial facilities worldwide. The company's instruments assess the condition of power transformers, circuit breakers, protection relays, and other substation apparatus, enabling asset managers to identify insulation degradation, winding faults, and mechanical defects before they result in costly failures or outages.

Doble's product line includes power system simulators used to validate protection relay schemes and SCADA systems, as well as high-voltage testers capable of measuring insulation resistance, power factor, and dielectric properties across a wide range of voltage classes. The company also offers software platforms for asset management and diagnostic data analysis.

Key Product Lines

• Power System Simulators — functional testing of protection relays, merging units, and intelligent electronic devices (IEDs) in substation environments
• High-Voltage Apparatus Testers — insulation power factor, tan delta, and capacitance measurements on transformers, bushings, and cables
• Transformer Diagnostic Equipment — frequency response analysis, winding resistance, and oil quality assessment tools

Industries Served

Doble equipment is used primarily by electric utilities, transmission and distribution network operators, independent power plants, and testing service providers. Applications include commissioning new substation assets, preventive maintenance of aging power transformers, protection relay testing during outage windows, and post-fault investigation in high-voltage networks.