The two wire circuit in Configuration 2 operates as follows: When the toggle switch is not activated or on, the automatic control device like a float or limit switch is connected in parallel so that some type of event would cause a control device to cut the load on or off without the presence of a operator.
#Forward and reverse motor control schmetic manual
Mostly referred to as hand-off- auto, a two wire control system is constructed to facilitate either the manual operation of a load by maintaining power to the coil through a toggle switch as seen in the diagram below, or automatically controlled by a control device similar to a liquid level switch. As the product is created there are a plethora of control devices that feed back into the control system to provide precision of movement and timing. Automatic control systems are at the heart of manufacturing. These systems are controlled by devices like a liquid level switch, pressure switch, float switch, flow switch, or any other device that census changes in a system automatically. In this system when the control device contact changes state due to an outside event without human intervention, this type of control circuit is called an automatic control circuit.Īutomatic control systems are a load in a circuit that is activated by an event in a controlled environment without the need for human intervention. Just as a switch can be used in a two wire control system to manually control a load, a control device that is used to sense a change of pressure or physical location can be an automatic two wire control system.
#Forward and reverse motor control schmetic full
When the switch is closed voltage is transmitted to the relay type device energizing the solenoid of the motor pulling in the armature which results in the main contacts of the pilot device providing full line voltage to the load being controlled.
Two wire controls can be connected not only to turn on lights but they may be connected to control motors.Ĭonfiguration 1 illustrates a switch connected to a motor starter coil which turns on a motor or resistive load not shown in control diagrams. This type of control system cannot sufficiently handle large amounts of current nor control loads that require more than one set of contacts that is required for single phase 240V 208 V or 480/277 circuit. Two wire controls are generally designed to carry small amounts of current.
Two-wire control, as seen in configuration 1, consists of a control device containing one set of contacts used to facilitate the on an off operation of a pilot device. The basic control circuits include two wire, three wire controls, manual /automatic, sequential control, stop/start, forward reverse, and jogging circuits.
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