CHAPTER 3 MEASURING STRATEGY
3.4 A CTUAL M EASURING S TRATEGY
3.4.3 Measurement schedule
The plan was to perform the measurements on the in-section electrical distribution network and then the mining equipment at one section before moving to the next section. This did not happen.
It suited the contractors better to measure one section’s distribution network the first week and the next section’s distribution network the following week. Table 3-10 shows the schedule for measurements on the distribution network of section 21 and 61.
Machine Component Phases to Variables to be measured be measured
CM
Cutter motor 1 1 Voltage and Current Cutter motor 2 1 Current
Gathering motor 1 1 Current Gathering motor 2 1 Current
Pump motor 1 Current
Conveyer motor 1 Current
LH Traction motor 1 Voltage and Current RH Traction motor 1 Voltage and Current Shuttle Car
Pump motor 1 Voltage and Current Conveyer motor 1 Current
Traction motor LH 1 Voltage and Current Traction motor RH 1 Voltage and Current Feeder Breaker
Conveyer motor 1 Voltage and Current Crusher motor 1 1 Current
Crusher motor 2 1 Current
Table 3-10: Measurement schedule for in-section electrical distribution networks.
Section 61 has shuttle cars with small flameproof enclosures. Even so, section 61 was still used to measure the in-section electrical distribution network because it is the top- producing section at Sasol Mining. The measurements on the mining equipment of section 61 were done on the mining equipment of section 51. The measurement schedule for measuring the mining equipment of section 21 can be seen in Table 3-11, and that of section 51 in Table 3-12.
Table 3-11: Mining equipment measurement schedule for section 21.
Measurements on the shuttle cars in section 21 could not be taken. The only shuttle car with a large flameproof enclosure in section 21 was taken to the surface for major repairs during the second week of measurements at section 21. This happened before measurements on the shuttle car could be done. Measurements were immediately done on the shuttle cars of section 51 to ensure that data on a shuttle car was obtained.
Meter Mo Tu We Th Fri
MAS - In-section In-section In-section Extra day
Distribution network Distribution network Distribution network
ION 7700 - Section MSU Section MSU Section MSU Extra day
Flashcard - Section Section Section -
Recorder CM CM CM
Meter Mo Tu We Th Fri
MAS In-section In-section In-section Extra day Extra day
Distribution network Distribution network Distribution network
ION 7700 Section MSU Section MSU Section MSU Extra day Extra day
Flashcard Section - - -
Recorder CM
Week 1 - Section 21
Week 2 - Section 61
Meter Mo Tu We Th Fri
ION 7700 - Section FB Section FB Section FB -
Crusher motor 1 Crusher motor 1 Crusher motor 1 Crusher motor 2 Crusher motor 2 Crusher motor 2 Conveyor motor Conveyor motor Conveyor motor
Meter Mo Tu We Th Fri
ION 7700 Section CM Section CM Section CM Section CM Section CM
Cutter motors X 2 Cutter motors X 2 Cutter motors X 2 Gathering head motors X 2 Gathering head motors X 2
Pump motor Pump motor Pump motor Conveyor motor Conveyor motor
Traction motors X 2
Meter Mo Tu We Th Fri
ION 7700 Section CM Section CM - - -
Gathering head motors X 2 Gathering head motors X 2 Conveyor motor Scrubber motor Traction motors X 2 Traction motors X 2
Week 1
Week 2
Week 3
Table 3-12: Mining equipment measurement schedule for section 51.
The measurement period on the equipment of section 51 was curtailed from three days to two days on each motor. The reason was that the shuttle car of section 21 would have been returned to production in the second week of measurements at section 51. If measurements at section 51 were shortened, it would mean that there would be a week left to do measurements on the shuttle car of section 21 before section 21 moved from Twistdraai Central to Twistdraai West Colliery. It was not possible to get the shuttle car back in section 21 before the section moved to Twistdraai West, as a there was a shortage in transportation. The shuttle car was therefore not measured.
Problems were also experienced with measurements on the pump motor of a shuttle car. No useable data could be obtained for a pump motor’s consumption at section 51.
Measurements were taken for one day on a shuttle car in section 50 to obtain data of the consumption of a shuttle car’s pump motor.
Measurements were also not performed on the feeder breaker of section 51 with the ION 7700 meter. Although the feeder breaker models were the same and the flameproof enclosures were the same, the layout of the protection equipment differed so much that the meter just could not fit inside. The MA 100 relay was used to do measurements on the feeder breaker, as can be seen in Table 3-12. The only useful data obtained were for the day that measurements were made on the conveyor motor.
Problems were also experienced with the active power measurements on the mining equipment. There were almost no useful power measurements on any of the motors.
The instrument did not always correctly measure the active power, because the phases measured did not always correlate. The voltage of phase A was measured,
Meter Mo Tu We Th Fri
ION 7700 Section SC Section SC - Section CM -
Pump motor Pump motor Cutter motors X 2
Conveyor motor Conveyor motor Pump motor
Traction motors X 2 Traction motors X 2
Meter Mo Tu We Th Fri
ION 7700 - Section CM Section CM Section CM -
Cutter motors X 2 Gathering head motors X 2 Gathering head motors X 2
Pump motor Conveyor motor Conveyor motor
Traction motors X 2 Traction motors X 2
MA 100 - Section FB Section FB Section FB -
Conveyor motor Crusher motor 1 Crusher motor 2 Week 5
Week 4
but what should have been the current of phase A was the current of phase B, for example, because the colour coding on the cables was wrong. This meant that the active power was calculated incorrectly. In the post-processing of data this phase-shift was corrected.