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What is a digital time relay

First, the basics of digital time leakage relay


The time leakage relay is a type of leakage relay that outputs an electrical shutdown or electrical on signal after a predetermined time when an input signal is given by an appliance or a machine.


Common functions of time leakage relays are:


A: On-delay Operation


F: Power-off delay (Off-delay Operation)


Y: Star Delta Delay (Star / Delta Operation)


C: With inst. Contact On-delay Operation


G: Interval-delay Operation


R: On-off repetitive delay operation


K: Off-signal delay Operation


1.Control power


The power leakage terminals of the time leakage relay can generally withstand an external surge voltage of 1500V. If the surge voltage exceeds this value, a surge absorption device must be used to prevent the time leakage relay from breakdown and burnout;


When the time leakage relay works repeatedly, the time from when the power is switched off to the next time the power is turned on (the rest time) must be greater than the reset time, otherwise, the time leakage relay that has not been completely reset will cause a delay time deviation in the next work Move, momentary or no action;


The power-on time of the power-off delay time leakage relay must be greater than 0.5 seconds in order to have sufficient energy reserves to ensure that the load is switched on or off according to a preset time after the power is turned off;


The power circuit of the time leakage relay is generally high impedance. Therefore, the leakage current after the power is cut off should be as small as possible (semiconductor or RC parallel contacts to switch the time leakage relay) to avoid false closing due to induced voltage. Malfunction due to power failure (for power-off delay type, the delay time after power failure will occur but the leakage relay does not release). In general, the residual voltage of the power terminal should be less than 20% of the rated voltage, and for the power-off delay type, it should be less than 7% of the rated voltage;


After the time leakage relay finishes its control work, try to avoid continuing to power on. After that time, continuous power supply will cause the product to heat up, which will accelerate the aging of electronic components and greatly shorten the service life.


2.Load connection


The output contact of the time leakage relay is limited by the volume of the product, so the load capacity is often not strong. Therefore, to protect the contact, you can connect absorption devices (such as RC, diode, Zener diode, etc.) in parallel at both ends of the contact. .


Do not use time leakage relays to directly control large-capacity loads. Some loads do not seem to be large, but the phenomenon of melting contacts occurs due to load current characteristics. The following table shows the relationship between the load form and the inrush current.