There are several types of engineering companies worldwide that perform preventive maintenance on electrical systems. Here are some common types:

1. Electrical Engineering Companies: These companies specialize in electrical engineering services, including the design, installation, and maintenance of electrical systems. They often offer preventive maintenance services to ensure the smooth operation and longevity of electrical equipment and infrastructure.
2. Facility Management Companies: Facility management companies oversee the maintenance and operations of various building systems, including electrical systems. They may have dedicated teams or subcontract electrical maintenance work to specialized engineering companies.
3. Industrial Engineering Companies: Industrial engineering companies focus on providing engineering solutions for industrial facilities and manufacturing plants. They often offer preventive maintenance services for the electrical systems within these facilities to ensure uninterrupted operations and compliance with safety regulations.
4. Power Generation and Distribution Companies: Power companies, including utility companies, play a crucial role in the maintenance of electrical systems. They regularly perform preventive maintenance on power generation plants, substations, and transmission and distribution networks to ensure reliable and efficient electricity supply.
5. Renewable Energy Companies: Companies specializing in renewable energy, such as solar and wind power, may perform preventive maintenance on the electrical systems associated with their installations. This includes inspecting and maintaining inverters, transformers, cables, and other components to maximize energy production and system performance.
6. Building Automation and Controls Companies: These companies focus on providing automation and control solutions for buildings, including the electrical systems. They may offer preventive maintenance services to optimize energy efficiency, monitor system performance, and detect potential issues in real-time.
7. Data Center Engineering Companies: Data centers require reliable and efficient electrical systems to support critical operations. Engineering companies specializing in data center design and maintenance often offer preventive maintenance services to ensure uninterrupted power supply and minimize the risk of equipment failures.

It’s important to note that the classification of engineering companies can vary, and many companies may offer a combination of services. The scope and specialization of preventive maintenance on electrical systems can also vary depending on the specific industry, client requirements, and regulatory standards in different regions.