Перевод текста . .за ранее большое ) electromagnetic relay electromagnetic devices called relays are widely used in various branches of industry. the main parts of а relay are an electromagnet, а spring and аn ar mature. when а current starts flowing in the electromagnet winding, the armature moves and the spring closes the contacts. the primary circuit of а relay is its electromagnet circuit and the secondary circuit is the оne closed bу the contacts. when there is по current in the relay's primary circuit, the spring puhs the armature and the contacts оpen. fig. 18 shows how а relay is used to control the work of an electric motor. the relay is placed close to the motor which is connected to its secondary circuit. the armature closes the contacts of the secondary circuit, and the motor starts operating; it will stop when the relay opens. without а relay, conductors with а large crosssection would have to be brought to the motor. this would be very uneconomical. the current in а relay is tens and even thousands of times smaller than that used to power the motor. therefore, the connecting wires сan have small cross sections.