Control of electromagnetic devices
Let's consider the devices used to pereyoklyucheniye in control circuits constant and with an alternating-current voltage up to 500 V.
Sequencers find broad application at distanyotsionny control of electrical machines and devices in schemes of automation of the electric drive. Depending on the ustyoroystvo and action of the including and switching contacts sequencers can be separated into two types:
- sequencers of push-button management;
- the sequencers rotating.
Push-button sequencers are used at manual and distance control, and the rotating sequencers — at distance and automatic control.
Sequencers can be put in action by the manual or foot drive (buttons of management, universal switches komandokontroller); electric actuator (komandokontroller) and working machine (traveling and limit switches).
Buttons of management are used to remote control of electromagnetic devices (contactors, the relay, magnetic actuators, etc.).
Buttons of management consist of one or several knopochyony elements. The contact device and the pin (button) which is mechanically connected with the contact ustroyyostvo enter the push-button element. Heads of pins (buttons) for convenience of service are supplied with texts: "start-up", "stop", "forward", "back" and others, are painted in different colors (the feet button — usually in krasyony).
In fig. 1 the push-button element of the device the upravleyoniya which consists from one closing and one razmykayuyoshchy the contacts which electrically are not connected among themselves is shown.
The electrical link which in the absence of tension in the chain of the managing coil or mechanical influence remains opened is called closing.
Disconnecting nazyyovatsya the electrical link which in the absence of the napryayozheniye in the chain of the managing coil or lack of mechanical impact on it is closed.
By pressing the head of the knopyoka of 1 ("feet") the movement of the button is transferred to the rod 2 which disconnects mobile contact the 3rd chain passing on the podvizhnoyom and motionless contact 4. When the button is released, the spring 5 returns it in the starting position.
By pressing the start-up button the mobile contact closes konyotakta of the electric circuit; when pressing the feet button podyovizhny the contact disconnects the chain. The springs got on pins return buttons in iskhodyony situation.
For the choice of buttons of management it is necessary to determine neobkhoyodimy execution by the way of protection (opened, protected, dustproof, explosion-proof), and then by number of shtifyot (one, two, three-bayonet); it is necessary to make the choice of kontakyot in size of permissible long current of loading (which does not exceed 15 A), in size of the permissible current, razyoryvayemy in the inductive chain (to 20 A), in size of the permissible current of inclusion (not higher than 60 And).Top