Ring Main Unit (RMU) Cycles: Air-Insulated Units Are Faster; Gas-Insulated Units Take Longer
RMU production cycles vary by insulation type: air-insulated units take 25–40 days, while gas-insulated units (C-GIS) and eco-friendly gas units take 40–60 days.
Industry experts note that the duration depends largely on gas-tightness processing; gas-insulated units require specific steps—gas-tight welding, leak detection, and gas filling—extending the cycle compared to air-insulated units.
Custom circuit configurations and export certifications add further time.
Production Cycle Reference (Based on Industry Practices)
- Air-insulated RMUs (HXGN series): 25–40 days;
- Gas-insulated units (SF6 insulation): 40–60 days (due to multiple gas-tightness processing steps);
- Eco-friendly gas units (dry air/N2): 45–65 days (longer scheduling due to new technology);
- Smart RMUs (motorized + telemetry): Standard cycle plus 10–20 days;
- Export orders: Domestic cycle plus 30–60 days for sea freight.
Factors Affecting the Cycle
First, insulation type.
Steps such as gas-tight welding, leak detection, and gas filling for gas-insulated units cannot be compressed, resulting in longer cycles than air-insulated units.
Second, component procurement.
Lead times for core components like vacuum interrupters and load-break switches.
Third, testing.
Scheduling for type tests (e.g., internal arc testing) and the need to book special tests in advance.
Fourth, customization level.
Requirements for specific circuit counts and switch types add to the production time.
Strategies to Shorten the Cycle
First, choose standard circuits.
Standard air-insulated units have the shortest production cycles.
Second, place orders early.
Avoid peak production scheduling periods.
Third, establish framework agreements with manufacturers for core components.
Fourth, adopt a parallel approach by conducting design and component procurement simultaneously.
Fifth, implement phased delivery, prioritizing the delivery of key cabinet units.
Pitfalls to Avoid
First, “inflated lead time estimates”—address this by stipulating lead times in the contract and including penalty clauses for non-compliance.
Second, “rushed airtightness processes”—compressing the schedule for airtightness testing creates leakage risks;
do not cut corners on this phase.
Third, “overlooked testing schedules”—type testing requires significant lead time, so schedule it well in advance.
Trends and Recommendations
Production lead times for ring main units (RMUs) are shortening as capacity for eco-friendly gas-insulated units expands, while digital scheduling brings greater transparency to timelines.
For buyers, the recommendation is to prioritize standardized circuit designs for air-insulated units, allow ample lead time for gas-insulated units, and explicitly include delivery deadlines in contracts.
Lead times depend on the insulation type: air-insulated units offer faster turnaround, while gas-insulated units provide stable, predictable schedules—selecting the technology effectively determines the lead time.
