Abstract:
An electric proximity detector or switch for detecting the presence or absence of electrically conductive objects is provided with interchangeable sensing heads arranged to be removably mounted on a basic switch unit or to be positioned at a location remote from the basic switch unit as desired.
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:
A timing attachment for a relay including a light source and detector and an apertured control member movable between the light source and detector to influence transmission of light therebetween, the movement of the control member being controlled by the relay, and the light source and detector providing initiation of the timing. Reversal of the timing attachment on the relay changes the position of the attachment relative to the control member to enable change from time delay after energization of the relay to time delay after de-energization or vice versa.