When the coil of the time relay is energized, each delay contact will act instantaneously. After the coil is cut off, the contact will be in the state of delayed position. When the set delay arrives, the delay contact will return to the initial state. The power failure delay type is due to its working state (no external power supply is required in the delay process) and the control contact is sucked and closed during the power failure delay process (the normally open contact should be kept on when it is turned on; When the normally closed contact becomes disconnection, it shall be in a state of disconnection.) the special transition (contrary to the working state of the contact of the conventional power-on delay type time relay) meets its control requirements. The power cut delay time relay is composed of the earliest separating devices (low delay precision and short delay time). The delay is accomplished by programming timing integrated circuit or CMOS counting frequency division integration. So as to satisfy the control situation of long delay of power cut.
A typical circuit
The overall composition of power failure delay relay includes power supply part of power failure delay relay (through buck, rectifier and filter) to provide power failure delay relay with built-in transient electromagnetic relay and 2 winding closed type R reset coil operation. The secondary power supply part (the delay part after power supply is cut off and the s-set coil of the 2 winding is working); Working part delay (programmable time integration or CMOS count frequency division integration); Driving part;
The power-cut delay type relay consisting of V2 P channel field effect tube, V3, V4 triode and relays is shown in figure 2. As follows: after the working power is added to the end, C1~C5 will complete the charging process according to its loop (charging time shall refer to the time specified in the product). At the same time, the resetting coil of the internal 2 winding latching relay (the switching contacts 4 and 6 in the virtual frame are switched on from the power supply to the disconnection state, and 4 and 8 are switched on), and the conversion end is connected with the corresponding external contacts, presenting a delayed working state).
When the power supply at the end is turned off, the corresponding relay enters the delayed working state. Of V2 p-channel field-effect tube, as the C4 after R6, discharge of RP2, causing a source S voltage lowering (in the state of electricity, because of UGS is lesser, ID is zero, the V2 work for the state), according to the field effect tube corresponding transfer characteristics (drain current ids and the relation curve between the gate source voltage VGS) when the VGS voltage reaches VGS (Th) voltage (open), V2 conduction. With the conduction of V2, leakage current ID is generated through R4 to generate corresponding voltage drop, enabling V3 triode to conduct work, and eventually leading to the conduction of V4. After the V4 conduction, the energy storage on the C5 capacitor will make the two-winding latching relay set the coil to energize, so that the delayed contact will return to the original state, thus completing the power supply delay.
The disadvantage of this circuit is that the delay parameter is not easy to set. It is usually necessary to adjust RP2 (control the C4 discharge circuit) and RP1 (determine the V2 grid voltage), and to calculate the C4 and C3 capacitance capacity parameters.
The delay circuit composed of integrated CD4060 is shown in figure 3. The circuit core delay consists of CD4060 and the delay setting is set by RP1 and C3. The internal 2-winding latching relay adopts DC24V (the relay with higher working voltage can reduce its driving current and make the driving part simpler). The end is added to the working power supply, and V1 triode works, so that its R reset coil is sucked and closed, and the internal contact is returned to the original state. C2 and C4 completed charging work.
When the terminal power supply is cut off, the corresponding power supply delay working state is entered. The pin of IC · 12 generates a level in R3 due to C1 discharge, which is increased by R4 to zero by the pin of · 12, so that the delay starts. The delay time drives the work of V2 through Q4~Q14 (according to the required delay time), and the oscillation stops when the delay reaches VD7. According to the delay, the C4 capacitance can be increased or decreased correspondingly (the capacity of C2 can be increased or decreased by parallel connection) to complete the work of s-set coil.
The line features convenient time delay setting, high precision delay, simple product adjustment, and is widely used at present.