1. On-site performance
Typical symptoms on site
- There are generators on site, but when the grid or prime power is shut down, drainage pumps, communications, lighting, ventilation or tailings equipment are still shut down.
- After a power outage, only manual closing, pulling, and load redistribution are required. The recovery speed depends on the experience of the personnel on duty.
- The generator can be started, but I don’t know which equipment to bring first. The key pumps are mixed with ordinary workshop loads to grab power.
- The ATS, switchgear, and cables may already be installed, but if the transfer logic is not clearly defined, the site still has to make ad hoc switching decisions during a real outage.
2. Risk causes
Root cause in the power-system design
Many mine sites regard “having a generator” as “having a backup”. In fact, the backup power needs to be clearly defined first: whether to temporarily provide the entire mine, or only to protect critical loads such as drainage, communications, lighting, ventilation and tailings.
If main, backup, critical power and non-critical loads are not separated, the generator may be connected to the wrong location during a power outage. After the prime power is lost, key equipment does not have an independent circuit and cannot be restored first.
ATS Buying a switch alone will not solve the problem. The switching sequence, load priority, loop zoning, delayed start and manual bypass must be planned in advance, otherwise power outage recovery will still rely on temporary operations by on-site personnel.
3. Scope of influence
Production, fuel, maintenance, safety and environmental risks all grow
- The shutdown of drainage, ventilation, communications, lighting or tailings equipment that should continue to operate will bring safety and environmental pressures in addition to the shutdown.
- Recovery is slow because the site has to find the right switches and decide which loads to restore; a single outage can turn into hours of production interruption.
- Manual switching is prone to misoperation and may load loads that should not be loaded first, thereby squeezing out the power margin of key equipment.
- The management thought that a backup power had been configured, but in actual power outage, key equipment was not protected, and the division of responsibilities and on-site command would become chaotic.
4. How to avoid before construction
What to confirm before procurement or expansion
- First divide the power in the mine site into prime power, backup power, critical power-guaranteed loads and non-critical loads. Don’t just write a backup generator in the equipment list.
- Identify what equipment must be restored first in the event of a power outage, such as dewatering pumps, tailings pumps, communications, lighting, ventilation, security monitoring, and necessary control systems.
- Make key loads into clear circuits, and cooperate with ATS, circuit breakers, delayed start and load priority to prevent the backup power from being occupied by ordinary loads.
- Conduct a power outage switching drill before going into production to confirm that automatic switching, manual bypass, recovery sequence and on-duty personnel operations can all be implemented.
5. On-site confirmation information
Site information needed for an engineering review
- The existing main power source is the power grid, diesel generator, parallel system, or temporary construction power.
- Photos of backup generators, ATS, low-voltage cabinets, switches, critical circuits and cable access points are available on site.
- A list of equipment that must maintain power during a power outage, as well as the allowable power outage time and startup method of each equipment.
- Recovery records after past power outages, including manual switching steps, recovery time, and which devices were unable to start in time.
