相间距离是三相之间的距离，在选择三相组合式过电压保护器时，用户需要考虑相间距离是否符合设备的安装要求，过小的相间距离可能导致设备散热不良或相间短路等问题，从而影响保护器的性能和使用寿命。
The phase to phase distance refers to the distance between three phases. When selecting a three-phase combination overvoltage protector, users need to consider whether the phase to phase distance meets the installation requirements of the equipment. A too small phase to phase distance may cause poor heat dissipation or phase to phase short circuits, thereby affecting the performance and service life of the protector.
5、附加功能：三相组合式过电压保护器可能具备多种附加功能，如过流保护、欠压保护、温度监测等，用户在选择时应根据实际需求，选择具备所需附加功能的保护器，以提高设备的安全性和可靠性。
5. Additional functions: The three-phase combined overvoltage protector may have multiple additional functions, such as overcurrent protection, undervoltage protection, temperature monitoring, etc. Users should choose the protector with the required additional functions according to their actual needs to improve the safety and reliability of the equipment.
6、使用场所：使用场所也是选择三相组合式过电压保护器时需要考虑的因素之一。不同的场所可能对保护器的尺寸、安装方式、防护等级等有不同的要求。用户根据具体场所的特点，选择符合要求的保护器。
6. Location of use: The location of use is also one of the factors to consider when choosing a three-phase combination overvoltage protector. Different places may have different requirements for the size, installation method, and protection level of the protector. Users choose protective devices that meet the requirements based on the specific characteristics of the location.
7、间隙类型：间隙类型决定了三相组合式过电压保护器在电压过高时的动作方式。不同类型的间隙具有不同的击穿电压和动作特性，用户应根据实际需求选择合适的间隙类型。
7. Gap type: The gap type determines the action mode of the three-phase combined overvoltage protector when the voltage is too high. Different types of gaps have different breakdown voltages and operating characteristics, and users should choose the appropriate gap type according to their actual needs.