Application of multi-period long delay time relay in automatic control field

Overview
In the field of time control, the delay specifications of the control time are usually selected according to the controlled time and the time delay accuracy. In order to ensure the reliability of the delay accuracy, the maximum delay range of the time relay should generally be consistent with the time required by the controlled electrical appliance (especially the time relay set by the knob). Only in this way can the relay reach the corresponding minimum setting error, so as to better and more effectively control the controlled circuit and device.

In order to meet the control of multiple time periods (usually the delay setting of the time relay is single and can only meet the control of a specific time period), there are multiple delay time periods in the time relay. It only needs to replace the time relay delay nameplate and adjust the magnification selection switch without adjusting the internal delay circuit to meet the above multi-time period control. Specifically, this product can replace multiple products, which is more convenient for users to choose and use, and saves control costs for users; and manufacturers have made the time relay model and delay specifications more reasonable and simplified. In short, this multi-time period time relay meets the characteristics of multi-function, miniaturization, cost saving and other characteristics in the control field, and is the development trend in the field of time relays.

At present, the domestic JSZ3 series time relay has multiple time periods (seven specifications of AA, B, C, D, E, F, G, 28 kinds of delay periods) and long delay (0.05s~24h) functions, and is an ideal product to replace the ST3P (Fuji, Japan) time relay. This series of products has been widely used in various control fields due to its advantages such as wide delay range, high delay accuracy, good reliability, long life, small size, and convenient time setting.

Time relay built-in chip
Chip pin

At present, the built-in delay chip of the time relay has many models: F6445C, RS6445C, LM8445, QA640896, etc. The above models are mainly different in the packaging form (single in-line and dual in-line), but the internal logic functions are the same. The following is an explanation of F6445C as an example:


Pin introduction
FIN-frequency input terminal: This terminal has a voltage comparator, which can form an oscillator with an external resistor-capacitor network to generate a main clock signal;
ADJ-voltage adjustment terminal: The adjustment level added to this terminal and the window comparator, discharge circuit, and RS trigger inside the circuit together form the main oscillator, which can easily adjust the main frequency;
VDD, VSS-positive and negative power supply terminals;
A, B-level preset terminal: frequency division selection terminal, the switch is suspended (or connected to a pull-down resistor) for low level (L), connected to VDD for high level (H);
TEST-test terminal (the test terminal is grounded or floating, if the external clock signal test terminal is connected to a high level) is a bidirectional output input terminal, which can be used by users to debug the system. In normal working state, "TEST" is suspended, which is the output terminal, outputting the 1024Hz square wave signal of the main oscillation circuit, which can be measured by an oscilloscope or frequency meter;
preset circuit setting

Setting time T=2/3×1024×N×R*••C*, where R*•C * are the delay potentiometer and delay capacitor respectively, and N is the frequency division coefficient.

Delay period and specifications (Table 2)
Multi-period time relay has 7 specifications (AA, B, C, D, E, F, G) and 28 delay periods, each specification has 4 delay periods, and the specification period consists of 2 nameplates (each has two delay periods on the positive and negative sides). According to the required control period, remove the delay knob and select the corresponding nameplate.


Delay setting
Take the AC specification time relay as an example:
T=2/3×1024×N×R*•C*=2/3×1024×1×800×103×10000×10-12=5.46 (S)
In the AC specification, N=1 (A 5 terminal; B 4 terminal)) are all connected to the high level "H". Based on this, the other time periods can be set by changing the frequency division coefficient N to 10, 60, and 360 respectively to set the delay time of the other three time periods of this specification (make A and B connected to "H" or "L" as needed, see Table 1 for details).

Working principle analysis


Principle analysis
An external working power supply of AC220V is connected, and a RU varistor is connected in parallel at the power input port (to absorb harmonic interference in the working power supply). After half-wave rectification by V1, one path is connected to the execution relay KA, and the other path is filtered by R8 and C4, and then added to the voltage regulator VZ through R7, LED2, and R6. C2 and C3 are connected in parallel to the voltage regulator to ensure stable DC voltage for the circuit chip. The external resistor-capacitor network at the FIN end generates the main oscillation frequency. After a fixed frequency division of 1024Hz, it is divided by 1, 10, 60, and 360 according to different frequencies (set by A and B ports according to requirements, see Table 1). After it matches the internal composite circuit (reaching the set delay), OUT outputs a high level, turning on the thyristor, closing the internal electromagnetic relay KA coil, and switching the contacts to control the external circuit; while OUT outputs a high level, the internal RS of the chip is set and the oscillation stops.

Conclusion
Multi-period long delay time relays can meet the needs of delay control (a single product can meet 4 periods) because of the convenient period selection (replace the nameplate that comes with it) and the convenient time setting of this product. It is widely used in the field of automatic control timing of machine tools and various equipment.