当频率变化低于
设置阈值f12。
它首先用于由发电机和热电联产提供的装置
植物。
大频率保护（功能）
该保护通过发出警报或接通断路器进行干预
当频率超过设定值时，在调整延时（t10）后打开
阈值f13。
它首先用于由发电机和热电联产提供的装置
植物。
过热保护（功能OT）
这种保护允许发出异常温度存在的信号
这可能会导致行程的电子部件出现故障
单元
如果温度达到一个阈值（70°C），跳闸装置应建议
操作员通过点亮“警告”led；如果温度达到二个阈值（85°C），除了
“警告”和“警报”LED，断路器将跳闸（通过启用
正确的参数）。
符合IEC60255-3的曲线过载保护
这种过载保护功能在协调中得到了应用
配有中压脱扣器和保险丝。
事实上，可以获得以下跳闸曲线之间的协调：
通过接近断路器跳闸曲线的斜率
中压脱扣器或保险丝，使低压和中压之间的时间-电流选择性为
获得。除了由电流阈值I1和跳闸时间定义外
t1，符合标准IEC 60255的曲线由参数“K”定义
“a”决定了它们的斜率。
参数如下：
曲线类型学
参数A B C
K 0.14 13.5 80.0
a 0.02 1.0 2.0
符合标准IEC 60255-3的曲线L可用于电子设备
用于T7和X1系列断路器以及
Emax系列断路器的PR122-PR123型电子跳闸装置。

open after the adjusted time-delay (t9) when the frequency varies below the set threshold f12. It is used above all for installations supplied by generators and co-generation plants. Protection against maximum frequency (function OF) This protection intervenes by generating an alarm or making the circuit-breaker open after the adjusted time-delay (t10) when the frequency exceeds the set threshold f13. It is used above all for installations supplied by generators and co-generation plants. Protection against overtemperature (function OT) This protection allows signaling of the presence of anomalous temperatures which might cause malfunctioning of the electronic components of the trip unit. If the temperature reaches the first threshold, (70°C), the trip unit shall advise the operator through the lightening up of the “warning” led; should the temperature reach the second threshold (85°C), besides the lightening up of the “warning” and “alarm” leds, the circuit-breaker would be tripped (by enabling the proper parameter). Overload protection with curves according to IEC60255-3 This protection function against overload finds its application in the co-ordination with MV releases and fuses. In fact it is possible to obtain a co-ordination among the tripping curves of the circuit-breakers by getting nearer to the slopes of the tripping curves of MV releases or fuses, so that time-current selectivity between LV and MV is obtained. Besides being defined by a current threshold I1 and by a trip time t1, the curves according to Std. IEC 60255 are defined by the parameters “K” and “a” which determine their slope. The parameters are the following: Curve typology Parameters A B C K 0.14 13.5 80.0 a 0.02 1.0 2.0 The curve L complying with Std. IEC 60255-3 is available both for the electronic trip units type PR332-PR333 for T7 and X1 series circuit-breakers, as well as for the electronic trip units type PR122-PR123 for Emax series circuit-breakers.