利用类别的特征详见下表1。
交流电中要求高的类别是AC23A，对于AC23A
装置必须能够连接等于额定电流10倍的电流
装置电流，以及断开等于额定电流8倍的电流
设备电流。
从结构角度来看，隔离开关是一种非常简单的
装置它没有配备过电流检测装置和相应的
电流自动中断。因此，隔离开关不能
用于自动保护系统中可能出现的过电流
发生故障时，必须由协调断路器提供保护。
这两种装置的组合允许在以下情况下使用隔离开关：
短路电流值大于定义隔离开关（后备保护）性能的电气参数的系统
见第3.4章。这仅适用于Isomax和Tmax隔离开关。
对于Emax/MS空气隔离开关，必须验证Icw的值
和Icm高于工厂和相应的短路值
峰值。

The characteristics of the utilization categories are detailed in Table 1 below. The most demanding category in alternating current is AC23A, for which the device must be capable of connecting a current equal to 10 times the rated current of the device, and of disconnecting a current equal to 8 times the rated current of the device. From the point of view of construction, the switch disconnector is a very simple device. It is not fitted with devices for overcurrent detection and the consequent automatic interruption of the current. Therefore the switch disconnector cannot be used for automatic protection against overcurrent which may occur in the case of failure, protection must be provided by a coordinated circuit-breaker. The combination of the two devices allows the use of switch disconnectors in systems in which the short-circuit current value is greater than the electrical parameters which define the performance of the disconnector (back-up protection see Chapter 3.4. This is valid only for Isomax and Tmax switch-disconnectors. For the Emax/MS air disconnectors, it must be verified that the values for Icw and Icm are higher to the values for short-circuit in the plant and correspondent peak, respectively.