各位 UL 987 30.3 关于运动部件护罩要求：
30.3 Some guards provided over moving parts are required to be of the self-restoring type – for example,
a guard on a saw and a guard on a jointer. Other features of a guard that shall be considered include:
a) Removability of the guard without the use of a tool;b) Removability for servicing and the need for replacement;
c) Strength and rigidity;
d) Completeness; and
e) Creation of a risk of injury to persons, such as pinch points, material hang-ups or jams,
restricted vision, or other conditions adversely affecting the ease of operation; and the necessity
for additional handling because of increased need for servicing – such as cleaning, unjamming,
and the like.

其中的a 怎么理解？不用工具就可以拆掉的运动部件护罩可以接受吗？

这个要具体情况具体分析，针对不同产品类型，在专门章节还有描述。
UL的这个系列标准有很多东西在判断上有很多主观的东西。