Safety and Protection Devices安全及保护装置

冻干机装有以下安全及保护装置，以确保设备在程序中的可靠性：

如果断电：

• 箱体和冷阱之间的主阀位置没有变化

• 所有其它的阀门都关闭以保持设备内部的完整性，真空泵抽气管上装的安全阀关闭以防止真空泄漏

• PLC 的电池可以保持储存的信息，PLC 程序也储存在EEPROM 中

• 来电后，程序将从断电时的程序点重新开始其它安全装置：

• 每个压缩机上装有一个压力开关，可以在排出口压力过高时，自动断开压缩机

• 在制冷管路中由于温度升高（主要是设备停机时）会造成低压侧的压力升高，每台压缩机上都有一个低压开关来防止压力升高，压缩机自动起动并向高压侧回收制冷剂。

• 如果在升华阶段，箱体真空上升到警戒点以上，搁板加热将会自动切断，如果真空继续上升，搁板将开始冷却

• 当过温时，2 个安全温度调节器会切断硅油加热器

• 如果压差下降，备份泵启动，一个压差开关监视器会监测循环泵（仅适用于双泵系统）

• 当缺油或者油泵不工作时，每台压缩机上的油压差开关会切断压缩机

• 所有的电机上都装有D立的过载切断开关

• 软件中的内部自锁程序可防止误操作，如当箱体和冷阱在真空状态下打开排水阀和化霜入口阀

The freeze dryer is equipped with the following safety and protection devices to ensure total process reliability:

In the event of power failure:

•The position of the main valve between the chamber and the ice condenser remains unchanged

•All other valves are closed to maintain the plant integrity. The valves in the inlet to the vacuum group are automatically closed to prevent leakage through the pumps.

•The PLC has battery backup, to ensure information is retained. The PLC program is also stored in non-volatile EEPROM memory.

•When power is re-established, the cycle is resumed from the same point where the power failure occurred 

Other safety features:

•A high pressure switch on each refrigeration compressor stops the compressor in the event of high discharge pressures.

•On each compressor, a low pressure switch prevents a pressure increase in the low-pressure side of the refrigeration circuit due to any temperature increase (typically when the plant stops). The compressor automatically starts and transfers the refrigerant to its high-pressure side.

•If the chamber vacuum rises above a programmed alarm point during the sublimation sequence, shelf heating is automatically switched off. If the vacuum continues to rise thereafter, shelf cooling is initiated.

•Two safety thermostats switch off the silicone oil heater should an over-temperature condition arise.

•A differential pressure switch monitors the performance of the duty circulation pump. If the differential pressure falls the standby pump is started (only applicable for machines with two circulation pumps).

•Differential oil pressure switches on each refrigeration compressor switch off the compressor in case of lack of oil or failure of the oil pump.

•All motors are fitted with individual over current breakers.

•Software interlocks prevent miss-operation of the equipment e.g. opening drain or defrost inlet valves when the chamber and condenser are under vacuum etc.

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