1. On-site performance
Typical symptoms on site
- The generator capacity has been increased, but the pressure drop is still significant when the crusher, water pump, air compressor or conveyor belt is started.
- Equipment near the generator set can run, while equipment farther away has trouble starting, trips frequently, or runs unstably.
- The temporary cables at the expansion site are getting longer and longer, with more and more joints. The problem is more obvious in rainy days, dust or high loads.
- The circuit breakers, low-voltage cabinets and cables still use the old configuration. The main unit has been upgraded to a larger one, but the power distribution system has not been re-examined.
2. Risk causes
Root cause in the power-system design
The generator is only responsible for sending out electricity, and the mine site also needs to deliver electricity stably to the equipment. The capacity of the low-voltage cabinet, circuit breaker setting, cable cross-section, line length and connector quality will all affect whether this part of the electricity can actually be used on site.
When lines are long, cables are undersized, joints are numerous, or zoning is unclear, voltage at the far end drops as soon as equipment starting current rises. The generator set may still have reserve capacity, but power cannot reach the downstream equipment reliably.
Expansion and phased construction are most prone to this problem. In the first stage, the cables can be temporarily pulled and used. When adding equipment in the second stage, if the power distribution and cables are not recalculated, faults will be concentrated and exposed.
3. Scope of influence
Production, fuel, maintenance, safety and environmental risks all grow
- Equipment failed to start, trial production was interrupted, and the site mistakenly assumed the generator was still undersized, so it kept increasing the generator set budget.
- Frequent voltage drops and trips increase the risk of failure of motors, control cabinets, contactors and cable connections.
- Maintenance personnel repeatedly checked generators and equipment, but ignored intermediate power distribution and line problems, which prolonged the downtime.
- Temporary lines carry high loads for a long time, which will increase joint heating, protection malfunctions and potential safety hazards.
4. How to avoid before construction
What to confirm before procurement or expansion
- Don’t just check generator kW or kVA. It is necessary to check the low-voltage cabinet, circuit breaker, cable cross-section, line length, connection method and equipment zoning at the same time.
- Draw the power route according to the location of the equipment, confirming how far each key equipment is from the power, which cables go, and which switches and connectors pass through.
- Before expansion, review whether the old power distribution system can still withstand the new load. If necessary, reserve independent circuits, enlarge cables, or adjust power distribution zones.
- During commissioning, record terminal voltage, startup sequence, and trip point so capacity is not assessed only from generator-end data.
5. On-site confirmation information
Site information needed for an engineering review
- Generator model, capacity, voltage, parallel mode, and photos of existing low-voltage cabinets and circuit breakers.
- The distance from the main equipment to the generator or distribution cabinet, line direction, cable specifications and connector locations.
- The name of the equipment that experienced voltage drop, tripping or startup failure, the startup method and the time when the problem occurred.
- Expansion phase plan, temporary line usage, future new equipment and whether the distribution zoning needs to be adjusted.
