Zhong Xin Tech-Zhong Xin Tech

Power-off delay relay: when the coil of the time relay is energized, each delay contact will act instantaneously. After the coil is powered off, the contact will be in the delay setting working state. When the set delay arrives, the delay contact will resume to the initial state. To control a motor, it is required to press the stop button for a period of time, and then restart the motor. In this case, it is necessary to use the power off delay relay to achieve the above functions. Power delay type because of its working state (in the delay process does not need external working power) and control contact in the power delay process of the suction contact (normally open contact into the state should be kept on the state; When the normally closed contact changes to the off state, it should be in the kept off state) to change the particularity (contrary to the working state of the contact of the conventional power delay type time relay) to meet its control requirements. Power delay time relay is composed of the earliest separation device (low delay precision, short delay time); Now the corresponding programmable timing integrated circuit or CMOS counting frequency division integration is used to complete the delay, compared with it, the delay accuracy is high, the delay time is long. In this way, it can meet the control situation of power failure and long delay. The overall composition of the power-off delay relay includes the power supply part of the power-off delay relay (after step-down, rectification and filtering) to provide the built-in transient electromagnetic relay of the power-off delay relay and the work of the 2-winding locking TYPE R reset coil); Secondary power supply (after power supply and power delay part and 2 winding locking type S setting coil); Time-delay working part (programmable timing integration or CMOS counting frequency division integration); Drive part; Due to the requirements of power failure delay relay to control contact conversion, bistable polarized electromagnetic relay (also known as 2-winding latching relay) is usually used to complete and meet the requirements of contact conversion. The inner coil and contacts are shown in the figure. The relay has an internal setting coil S and a reset coil R, which is a latching structure relay that can maintain the setting state or reset state. When the current flows through the set coil S, the magnetic flux is generated in the magnetic circuit composed of the inner iron core, magnet and armature and the working air gap, and the magnetic field is established in the working air gap to generate electromagnetic suction and attract the armature. In the coil current reaches a certain ＆#118alue (that is, the action ＆#118alue), the electromagnetic suction is enough to overcome the resistance of the magnet suction and contact reeds, driven armature group action, armature moves the card to move the contact reeds on both ends of the group, the dynamic contact closure and moving contact groups disconnect, thus make contact conversion, and keep the setting state. When the power delay is over, current flows through the reset coil R (no current exists in the set coil), and the working state is the same as that of the set coil. Finally, the closed dynamic contact is disconnected, and the disconnected dynamic contact is closed again. Attention should be paid to the polarity of reset coil S and reset coil R. In view of the application of power delay relay, usually in the selection of internal latch-type relay, the following conditions should be referred to as the selection criteria: low power consumption, high sensitivity, large load, high insulation voltage, vibration and impact resistance; Only in this way can the power delay work reliably. Especially in the aspect of vibration resistance and impact resistance, due to its own internal structure particularity, the corresponding power failure delay relay should pay attention to its aspects during installation and use, so as to avoid the contact misconversion of latching relay due to vibration or impact. In relay working voltage choice, like power relay, in principle, take the working voltage of coil electromagnetic relay, this setting can be added to reduce coil r s and reset coil current ＆#118alue, so as to ensure the electromagnetic relay to reset after the delay coil current action to meet the required rating of the action ＆#118alue, and fully guarantee the reliable transfer contact work. In some of the power delay time relays, the internal relay also has a winding locking type relay, the relay has a coil (S, R) and is a kind of locking relay can switch according to the polarity of the applied voltage and maintain the setting or reset state. But because the voltage polarity of the working coil must be changed, the control circuit is more complicated and rarely used. 2 winding locking relay is usually used to make the internal control circuit simple and reliable.