参考资料

1. https://support.industry.siemens.com/cs/document/16818490/mean-time-between-failures-(mtbf)-list-for-simatic-products?dti=0&lc=en-CN

2. https://www.ad.siemens.com.cn/productportal/prods/published/Inf/Inf_6.1/Inf_6.1.html

Furthermore, the average time of failure-free operation during the mission is known as the Mean Time Between Failure (MTBF 平均失效间隔时间). This term is based on the assumption that when a failure occurs, the system does not generally remain in the down state for the rest of time the mission lasts, but is renewed or repaired.

Additionally, the time required for renewal or repair (i.e. from the start of the down state to the restoration of the up state) is known as the Mean Time to Repair (MTTR 平均修复时间), often also called Mean Down Time (MDT).
If repairs are always carried out upon occurrence of a failure, then the duration of the mission is the sum of MTBF and MTTR.
For this standard, a practical case of availability is:
A=MTBF/(MTBF+MTTR)

MLFB:6ES7518-4JP00-0AB0 CPU-1518HF-4 PN with Display(CPU控制器)

MTBF:10.33 years

MLFB:6ES7960-1FB00-0AA5(光纤及接头)

MTBF:760.20 years

MLFB:6ES7505-0KA00-0AB0 (DC 25W电源)

MTBF: 28.0 years

系统模块    "MTBF(hours)"    "MTBF(years)"    "Availability %(4H) "    "Availability %(12H) "    "Availability %(48H) "    "Availability %(72H)"
Powersupply-电源    245280    28    99.99836924    99.99510787    99.98043436    99.97065441
Controller-控制器    90490.8    10.33    99.99557986    99.98674074    99.94698406    99.92049716
"Redundancy module
-冗余模块"    6659352    760.2    99.99993993    99.9998198    99.99927921    99.99891883
                        
"Simplex Availability
-单机可用性(有冗余模块)"            99.9938891    99.9816691    99.92670852    99.8900949
"Redundant Availability
-冗余双机可用性"            99.99999963    99.99999664    99.99994628    99.99987921

那么如何计算可靠性呢?

可用性和可靠性之间的换算公式是?