5 RAMS要求 RAMS requirement
5.1 可靠性 Reliability
满足系统平均故障时间间隔（MTBF）要求：系统平均故障间隔时间：≧105小时。
Satisfy system mean time between failures (MTBF): system mean time between failures: ≧105 hours.
为提高设备的可靠性，安全计算机单元采用以下结构。
To improve the equipment reliability, VC unit adopts the following architecture:
子系统
Subsystem 结构
Structure 原因
Causes 备注
Remarks
安全计算机单元
Safe-load computer unit 2取2×2
2 shall be 2×2 安全计算机单元是系统的核心单元，该单元的失效将是致命的，为此采用2取2×2的结构。
Safe-load computer unit is the core unit of system, failure of this unit will be vital. Therefore 2 shall be of 2×2 structure.
5.2 可用性 Availability
1. 系统的可用性应满足下述要求：系统的可用性大于99.99％。
The system availability shall satisfy the following requirement: system availability shall be more than 99.99%.
2. 为提高可用性，系统应采用如下结构：如下表所示：
In order to improve availability, system shall be of the following structure: as per the table below:
子系统Subsystem 结构Structure 原因Causes 备注Remarks
记录单元 Record unit 非冗余Non-redundancy 作为记录装置，该单元失效将不会影响系统的正常运行。
As a recording device, failure of this unit will not impact the normal operation of the system.
BTM 冗余Redundancy 应答器信息是控制列车运行的基本要素之一，为提高可用性，采用冗余结构。Balise information is one of the elements for train speed control, and redundancy structure is used in order to improve availability. 目前供货商仅提供非冗余的结构。应考虑该系统修改为冗余结构。For the time being, the supplier only supplies non- redundancy structure. The system shall be modified as redundancy structure.
DMI 非冗余Non-redundancy 目前该单元为非冗余结构，应考虑修改为冗余结构。The unit is of non-redundant structure for the time being, and shall be modified as redundancy structure. 应考虑冗余设计。本次开发设备预留与DMI的冗余接口。It shall be modified as redundancy design The developed equipment will reserve the redundant interface with DMI.
与列车接口单元Train interface unit 非冗余Non-redundancy
轨道电路信息接收天线Orbit circuit info receiving antenna 冗余Redundancy 轨道电路信息是列车运行的基本依据。Track circuit information is the base of train operation.
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注：DMI、BTM不属于本项目开发范围。
Note: The project scope does not include DMI and BTM.
5.3 可维护性 Maintainability
1. 硬件设备应该做到模块化、标准化、可测试：
The hardware equipment shall be modularized, standardized and testable.
a) 根据系统的不同功能进行模块划分；
The system shall be modularized according to different functions.
b) 相同模块应按统一标准设计，可实现相同模块的互换；
The same module shall be designed according to the uniform standard in order to allow interchange of the same module.
c) 系统应可进行板级白盒测试；
System shall be suitable for white box test.
d) 对于不同类型的列车采用相同的硬件。
The same hardware shall be used on train of different types.
2. 系统设计应包括有适当的测试点、故障隔离及诊断措施。
System design shall include proper test point, failure isolation and diagnose measure.
a) 对于电压输入、输出及关键信号应有测试点；
Test point shall be arranged for voltage input & output and key signal.
b) 对于紧急、最大常用制动的输出应具有故障诊断及故障隔离措施；
Output of emergent, important normal braking shall be provided with failure diagnosis and failure isolation measure.
c) 智能板应具有故障自诊断功能；
Intelligent board shall be design with failure self-diagnostic function.
d) 非智能板的关键电路应具有故障自诊断功能。
The key circuit of unintelligent board shall be designed with failure self-diagnostic function.
3. 每个模块应具有运行、故障指示灯。
Each module shall be designed with operation and failure lamp.
4. MTTR时间为8小时 MTTR is 8 hours
5. 维护方式包括Maintenance methods include
a) 日常紧急制动测试 Routine emergency braking test
b) 车载设备日常自检测 Routine train-borne equipment self-test
c) 每月测试 Monthly test
d) 半年测试 Semi-annual testing
e) 三年测试 Three-year test
f) 十年测试 Ten-year tests
5.4 安全性能 Safety feature
1. 满足系统安全功能每小时出现危险故障的概率要求：具体要求见下表：
Probability requirement of critical failure with system safety per hour: details as per the table below.
序号
No. 项目
Item 每小时危险故障概率
Per-hour critical failure probability 备注
Remarks
1 紧急、最大常用制动
Emergency max. normal braking 10-9
2. 系统最大常用制动（NB7）与紧急制动（EB）应满足SIL4级的要求。
System max. normal braking (NB7) and emergency braking (EB) shall satisfy grade SIL4 requirement.
3. 最大常用制动故障时，输出紧急制动。
In case of max normal braking failure, output emergency braking.
4. 系统1、4级常用制动及切除牵引应满足SIL2级要求。系统的安全性由最大常用制动和紧急制动保证。系统1、4级常用制动只是为了满足列车乘坐的舒适性，故只需满足SIL2级。
System grade 1, grade 4 normal braking and traction cutoff shall satisfy grade SIL2 requirement. System safety can be guaranteed by the maximum normal braking and emergency braking. Grade 1 and 4 normal braking is only used to satisfy the amenity of train riding. Thus, it is only necessary to satisfy the SIL2 level.
5. 车载设备应当使用两个车轮的速度信号进行相互比较，确定所使用信号的安全性。
The on-vehicle equipment shall compare the speed signal of two wheels and determine the safety of signal used.
6. 车载设备应当对ROM、RAM进行校验。
On-vehicle equipment shall verify ROM and RAM.
7. 对于输出的控制结果应进行校验。
The output control result shall be verified.
