公开(公告)号：US3851216A

公开(公告)日：1974-11-26

申请号：US41092773

申请日：1973-10-29

Applicant: SQUARE D CO

Inventor： CLARKE G ,  HARRIS G

IPC: H02H3/06 ,  H02H3/093 ,  H02H3/34 ,  H02H7/08

CPC classification number: H02H3/093 ,  H02H3/06 ,  H02H3/34

Abstract: An apparatus for detecting abnormal current in an electric motor circuit. The apparatus includes solid state components which are arranged to detect normal balanced overload conditions, and unbalanced, single phase, and reversed phase sequence conditions, as well as ground fault conditions in the motor circuit and provide an output when any of the detected conditions could damage the motor. The apparatus includes a circuit for charging a capacitor at a non-linear timed rate in response to the magnitude of current in the motor circuit, a level detecting circuit for sensing and providing an output signal if the voltage across the capacitor exceeds a predetermined threshold potential, a bistable switch with a relay for responding to the output from the level detecting circuit to energize the relay and thereby interrupt the current to the motor circuit, and a timing circuit including a timing capacitor which provides the energy for cancelling the residual retentive magnetic flux in the relay when the charge on the capacitor has decreased to a predetermined level.

Abstract translation: 一种用于检测电动机电路中的异常电流的装置。 该装置包括固态元件，其被布置成检测正常平衡过载条件以及不平衡，单相和反相序列条件以及电动机电路中的接地故障状况，并且当任何检测到的条件可能损坏时提供输出 电机。 该装置包括用于响应于电动机电路中的电流的大小而以非线性定时速率对电容器充电的电路;电平检测电路，用于如果电容器两端的电压超过预定阈值电位则检测并提供输出信号 ，具有用于响应于电平检测电路的输出的继电器的双稳态开关，以对继电器通电，从而中断到电动机电路的电流;以及定时电路，包括提供用于消除残余保持磁通量的能量的定时电容器 当电容器上的电荷降低到预定水平时，在继电器中。