This relay provides a “Time Delay” between the energizing or de-energizing of the coil and movement of the armature. The switching operation is achieved by energizing or de energizing the coil in the relay. A Relay is an electromechanical device that acts as a switch between two terminals. Providing time-delayed switching to start a motor, control a load, or affect a process, time delay circuits are typically used in industrial applications and consumers equipment such as in voltage stabilizer.Ī 555 timer ic and relay is the major components used in this work. Overvoltage protection: Time Delay Switching device can be equipped with addition of overvoltage protection which reduces risk of supplied device defect or malfunction due to lighting strikes or other overvoltage source. Often, this inrush current is not given sufficient consideration or is overlooked, which can lead to unexpected circumstances later on. Besides this, such high current pulses produce voltage dips in the supply voltage, which in turn can cause malfunctions in other consumer circuits powered from the same supply. Circuit breakers and switches have to be designed for these peak currents to prevent unpredictable trips or contact welding. This peak currents (Iinr_p) can be extremely high, from few times nominal device current (Inom) to few 10 times nominal current, depends on device topology and its built-in inrush protection. When electrical and electronic devices are switched on, they load the supply network momentarily with high current pulses, called inrush current. It gives power to the device only after one to two minutes of delay after the power is switched on. The time delay relay circuit described here is intended for this purpose. (d) Describe the action of a 555 monostable timer and then use the equation T= 1.1 RC, where T is the pulse duration. (c) Describe how the time delay may be changed by varying R and/or C. (b) Describe how the voltage across a charging or discharging capacitor in a RC circuit varies with time, including the interpretation of decay graphs for RC networks. (a) Describe how a RC network can produce a time delay. The main aim of this work is to construct a device that switches on a load after a period of the set time.Īt the end of this work the student involved should be able to: Such relays are called Time Delay Relays.Ī Time Delay Relay consists of a normal electromechanical relay along with a control circuit to control the relay operation and timing.Ī delay used to separate the occurrence of two events, especially in a mechanical or electronic device. These relays provide a “Time Delay” between the energizing or de-energizing of the coil and movement of the armature. A 5v voltage regulator is used for giving 5v regular supply to the circuit.Ī Relay is an electromechanical device that acts as a switch between two terminals. In this work a 9 V battery and 5V optional relay was used for switching the AC load. It also has a potentiometer to adjust the time delay, where you can increase of decrease the time delay by just rotating the potentiometer. This circuit consists of 2 switches one for start the delay time and other for reset. In this project is on a Simple Time Delay Circuit Using 555 Timer IC. If a short delay is provided, such damages can be avoided. The spurious spike in the power supply when power resumes is due to heavy magnetic flux in the distribution transformer in the mains network. Inrush current at power on or power resumes after a power failure can cause unexpected damage in power supply of electronic devices. This prevents deleterious effects due to inrush current and spurious spikes at power on. The power supply of these modern electronic devices is vulnerable to spikes in the mains line so it gives a time delay of one minute before applying power to the device. The contact load ratings are specified for each specific type of time delay relay. The output contacts on the electromechanical output relay are direct wired to the output terminals. There are many choices of timing adjustments from calibrated external knobs, DIP switches, thumbwheel switches, or recessed potentiometer. Time delay relays have a broad choice of timing ranges from less than one second to many days. The control circuit is comprised of solid state components and timing circuits that control operation of the relay and timing range. A Time Delay relay is a combination of an electromechanical output relay and a control circuit. Time Delay is defined as the controlled period between the functioning of two events.
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