Answer Happy

Outel is a large manufacturing company located in northern Peninsular of Malaysia. The company experienced problems with random failures in several motor operations powered by adjustable speed drives (ASD). The company appointed TNC Consultancy to thoroughly investigate the problems and recommend mitigation device. The first part of your investigation is to assess the severity of the disturbance to the whole plant. Summary of voltage variation events recorded at the factory for a period of 90 days shown in Table 3. The second part of your investigation is to estimate the cost impact due to the events. Table 4 combines the weighting factors associated with categories of voltage variation to determine the equivalent economic impact. Finally, the last part is to choose the suitable mitigation device. Table 5 shows few mitigation devices with the specifications. i) Determine the total number of voltage sag events ii) Make a table and classify the measured voltage sag according to IEEE 1159-1995 for instantaneous, momentary and temporary with the respective number of events. iii) Calculate the rms variation site indices for each voltage sag class and complete Table 6. Calculate each index for 30 days to comply with the standard. iv) Determine the total equivalent economic impact and complete Table 4. v) Calculate the overall economic cost, assume every disturbance costs RM50,000. vi) Suggest the suitable mitigation device for this factory with TWO (2) strong justifications.
Voltage L1,L2,L3 V> 110% 85% ≤V <90% 71% ≤V ≤ 84% 41% ≤ V≤ 70% 10% ≤ V≤ 40% 10-20ms 5 6 1 0 0 Table 3 21 - 100ms 2 10 13 5 0 101 - 600ms 2 17 20 5 0 0.61 1s 1 5 0 1 0
Category of event Interruption Sag with minimum voltage below 40% Sag with minimum voltage between 41-70% Sag with minimum voltage between 71-90% Voltage sag mitigation device Remaining voltage Operating principle Initial cost Operating cost per year Weighting for economic analysis 1.0 0.8 0.4 0.1 Constant voltage transformer 0.3 p.u This device can be used at the equipment level or plant level. It offers protection only for voltage sags. No need battery. RM 800/KVA Table 4 1% of initial cost Table 5 UPS No. of events 0.85 p.u This device can be used at equipment level or plant level or even utility level. Need battery. RM 1500/KVA 2.5% of initial cost Coil hold in devices Total equivalent economic impact None Dynamic voltage restorer 0.25 p.u 0.5 p.u This device can be used at the plant and utility This device is the equipment level solution. Mitigate the effect of level. It can voltage sags on individual relays and contactors. work with or without battery. RM 530/KVA RM 700/KVA 5% of initial cost
X 110 90 70 SARFIX Table 6 SIARFIX SMARFIX