Reliability modeling of power transformers with maintenance outage

Figures & data

Figure 1. A typical power transformer showing major components.

Figure 2. State transition diagram of Group 1.

Figure 3. State transition diagram of each component in Group 2.

Figure 4. Series structure in Group 2.

Figure 5. Markov state transition diagram of the transformer with maintenance outage.

Table 1.  Typical parameter configuration for numerical evaluation.

Parameters	Value	Unit	Description
	0.005	Failures/yes	Total fault rate
	1000	Hours	Repair time
β	0.5		Proportion
	0.1	Failures/yes	Failure rate
	0.2	Outages/yes	Maintenance rate
	100	Hours	Maintenance time
	0.001	Failures/yes	Failure rate
	480	Hours	Repair time
	0.004	Failures/yes	Failure rate
	360	Hours	Repair time
	0.003	Failures/yes	Failure rate
	360	Hours	Repair time
	0.002	Failures/yes	Failure rate
	72	Hours	Repair time
	0.003	Failures/yes	Failure rate
	48	Hours	Repair time

Figure 6. Probability of full capacity P(E₁) vs. windings failure rate multiplier (increased by 10 times).

Figure 7. Probability of zero capacity due to maintenance P(E₄) vs. windings failure rate multiplier (increased by 10 times).

Figure 8. System unavailability U vs. windings failure rate multiplier (increased by 10 times).

Figure 9. Probability of full capacity P(E₁) vs. proportion factor β.

Figure 10. Probability of derated capacity P(E₂) vs. proportion β.

Figure 11. System unavailability U vs. proportion factor β.

Figure 12. Probability of full capacity P(E₁) vs. maintenance rate multiplier (increased by 10 times).

Figure 13. Probability of derated capacity P(E₂) vs. maintenance rate multiplier (increased by 10 times).

Figure 14. Probability of zero capacity due to component down P(E₃) vs. maintenance rate multiplier (increased by 10 times).

Figure 15. Probability of zero capacity due to maintenance P(E₄) vs. maintenance rate multiplier (increased by 10 times).