Retrofit of Power Distribution System at Automotive Parts Factory

The client is an automotive parts manufacturer in East China. Its original power distribution system has been operational for over a decade, featuring molded case circuit breakers (MCCBs) with low breaking capacity and poor coordination between upstream and downstream protection settings. A short-circuit fault at any workstation can cause a complete production line shutdown, resulting in significant single-incident downtime losses.

Before the upgrade, we worked with the client's electrical lead to review the single-line diagram and load schedule. We verified the calculated currents, short-circuit levels, and cable ampacities for each circuit. This confirmed that the existing protective device settings no longer match the actual loads. Additionally, inspection records indicated elevated contact temperatures in some cabinet components.

Replace the main and branch protection elements with ZPM3 series electronic molded case circuit breakers, recalibrating long-time delay, short-time delay, and instantaneous settings per selective coordination principles. Motor circuits in the welding workshop use a combination of ZPC1 contactors and ZPR1 thermal overload relays to provide overload and phase-loss protection. New load-dense areas are supplied via distribution from unified ZGGD switchgear cabinets.

Components and complete switchgear are manufactured and factory-tested at the same facility. They are delivered in batches according to scheduled site outages, coordinated with customer-specific area shutdowns for construction. Upon completion, we provide a setting comparison table and factory test records to support the client's internal equipment archiving and future inspection comparisons.