Finder time relaySelection principle of
When selecting finder time relay, you can generally follow the following rules:
1. According to the needs of the controlled circuit, decide whether the finder time relay is powered on delay type or powered off delay type.
2. The voltage of the attracting winding of the finder time relay is selected according to the voltage of the controlled circuit.
3. If the time delay requirement is high, you can choose transistor type finder time relay or electric type finder time relay; If the time delay requirement is not high, the air damping finder time relay can be selected.
4. Select the finder time relay within the time delay range as required.
Precautions for finder time relay
1. Control power supply: when using, check whether the voltage and frequency of the power supply are consistent with the rated voltage and frequency of the finder time relay.
1.1. Connect the wires correctly according to the product wiring diagram, pay special attention to DC products, connect the power supply, and check the positive and negative polarity of the power supply.
1.2 the input of the power-off delay finder time relay is a high impedance loop. After power failure, it sometimes does not work due to the influence of induced voltage and leakage current. In this case, a leakage resistance should be connected between the power terminals of the finder time relay so that the voltage on the power terminal is less than 7% of the rated voltage in case of power failure.
1.3 the power supply voltage of finder time relay is allowed to fluctuate within the range of 85% - 110% of the rated power supply voltage.
1.4. When continuously powered on at high temperature, it should be noted that the allowable power supply voltage fluctuation range is 90% - 110%. Long time operation at high temperature will accelerate the aging of electronic components due to internal heating. Therefore, it is possible to avoid being in the action state for a long time by changing the control circuit.
2. Control signal input
2.1 When using contactless elements to control finder time relay, its output part should be isolated by optocoupler as far as possible.
2.2. The power supply and output circuit ends of the control signal output device should use isolation transformers as far as possible, and the output circuit should not be grounded. The power supply of finder time relay uses isolation transformer.
2.3. The control signal input line shall be as short as possible, shielded or special metal wiring pipe shall be used, and it shall be as far away from the power line and high-voltage line as possible to avoid interference and misoperation.
3. Rest time
When the finder time relay delays repeatedly, the rest time between two times should be greater than the specified reset time. If it is less than the reset time, it may cause delay deviation, flashing, inaction or panic.
4. Control of power-off delay and disconnection delay
4.1. The minimum power on time of finder time relay with power-off delay type delay less than 180s shall be greater than or equal to 2S; However, the minimum control input time of finder time relay with disconnection delay shall be greater than 50ms.
4.2. The contact is restored to the initial state
Before the power-off delay relay is put into use in the control circuit, if the contact of the product is not reset to the initial state, the delay time of the product should be set to the minimum time. Turn on the power of the product for 2 seconds and then turn off the power. After the delay time reaches the minimum setting time, the product can be reset to the initial state.