How a Manufacturing Plant Reduced Electrical Faults by 45% with the DZ15LE RCBO

Customer Background

A mid-sized automotive parts manufacturer in Guangdong, China, operates two production lines with over 200 machines. The plant runs 24/7 to meet tight delivery schedules. Despite routine maintenance, electrical faults caused frequent production stoppages, leading to annual losses exceeding $50,000 in downtime and rework.

Challenges and Pain Points

The previous protection system used separate MCBs and RCDs from different suppliers. Coordination issues led to nuisance tripping—up to 8 false trips per week. Each trip required a 30-minute reset and inspection. Worse, actual leakage faults sometimes went undetected because the RCDs lacked overamperage discrimination. The plant manager described the situation as "a guessing game—we never knew if a trip was real or false."

Another problem: the existing RCDs had a residual amperage sensitivity of 30 mA, but aging equipment caused gradual leakage increases that triggered alarms prematurely. The maintenance team spent 10 hours weekly troubleshooting non-issues.

Why the DZ15LE RCBO?

The plant assessed three options: upgrading individual components, installing a centralized monitoring system, or replacing all units with integrated RCBOs. The DZ15LE from SINGI offered a key advantage: it combined overamperage and residual amperage protection in one device, eliminating coordination mismatches. Its adjustable residual amperage setting (30/100/300 mA) allowed fine-tuning for each machine's leakage profile., the DZ15LE’s compact size (2-module width) fit existing distribution boards without modification.

Cost was another factor: at $12 per unit, the DZ15LE was 10% cheaper than sourcing separate MCB and RCD pairs. The decision was made after a 2-week trial on one production line showed a 70% drop in nuisance trips.

Implementation Process

The project took four weeks. Key steps:

• Audit and Mapping: The team cataloged all circuits, measuring baseline leakage and overamperage levels. Each machine’s sensitivity requirement was recorded.
• Phased Replacement: First, high-priority machines with frequent faults were upgraded. Then, the remaining circuits were swapped over three weekends to minimize disruption.
• Commissioning: Each DZ15LE was set to the appropriate residual amperage threshold (30 mA for critical, 100 mA for general loads). A final test confirmed proper tripping times (<0.1 s per GB/T 6829-2017).
• Training: Maintenance staff received a 2-hour session on interpreting trip indicators and adjusting settings.

A difficulty arose with an older injection molding machine that produced transient leakage spikes. By setting the DZ15LE to 100 mA with a short delay, false trips were eliminated without compromising safety.

Quantifiable Results

After three months of operation:

• False trips reduced by 45% (from 8 to 4 per month).
• Annual downtime costs slashed from $50,000 to $12,000—a 76% reduction.
• Maintenance hours cut by 60% (from 10 to 4 hours per week).
• Production line OEE (Overall Equipment Effectiveness) increased by 12%.

The plant also reported zero undetected leakage faults, improving worker safety.

Client Testimonial

“The DZ15LE solved our coordination nightmare. We now trust our protection system, and the staff can focus on real production issues instead of chasing ghosts.” — Electrical Supervisor, Guangdong Automotive Components Plant

Lessons and Recommendations

For other manufacturers considering RCBO upgrades:

• Measure before you replace: Baseline leakage data ensures correct sensitivity choice—don’t assume one setting fits all.
• Phase the rollout: Start with problem circuits to prove value ; then expand to gain management buy-in.
• Train the team: Understanding adjustable trip thresholds prevents misuse and speeds up troubleshooting.

If doing the project again, the plant would have conducted the audit earlier—they estimate it could have saved an additional 2 weeks of downtime.

References:

GB/T 6829-2017. Residual amperage operated circuit-breakers with or without overamperage protection for household and similar uses (RCBOs) [S]. 2017. Link

Chen G, Mou X. Study on the coordination between MCB and RCBO in low-volt-level power distribution systems [J]. Electrical Engineering, 2022, 104(3): 1823-1835.

Cost-Effective Sensor for Residual Amperage Detection in Residential DC Microgrids. Link