• Skip to main content
  • Skip to primary sidebar

Homemade Circuit Projects

Get free circuit help 24/7

New Projects | Privacy Policy | About us | Contact | Disclaimer | Copyright | Videos 

You are here: Home / Home Electrical Circuits / Mains AC Overload protection Circuit for Voltage Stabilizers

Mains AC Overload protection Circuit for Voltage Stabilizers

Last Updated on January 23, 2020 by Swagatam 82 Comments

In this article we discuss how to make a cheap yet effective mains operated AC overload and over-current protector circuit using very ordinary discrete components.

Introduction

I have published a few mains voltage stabilizer circuits in this blog, these units are designed and intended for safeguarding the connected appliances at their outputs.

However these equipment lack one protection which is the overload protection.

The Importance of an Overload Protection Circuit

A particular stabilizer unit may be rated for handling a maximum specified limit of power, beyond which it's effects may start diluting or might become inefficient.

Overloading a voltage stabilizer might also result in heating of the transformer and fire hazards.

A simple circuit shown below may be incorporated with a stabilizer circuit or any such protection circuit for reinforcing the safeguarding capabilities of the units.

How it Works

The diagram shows a very simple and straightforward configuration where only a couple of transistors and few other passive parts are used for forming the intending design.

The mains stabilized AC is derived from the stabilizer outputs and allowed to switch through another RL1, via its N/C contacts.

One of the wires of the AC mains connections is added with a series resistor of a calculated value.

As the load across the mains output increases, a proportionate magnitude of voltage starts developing across this resistor.

The value of the resistor is so selected that the voltage across it becomes just enough to light up a connected LED in response to a load that might be considered as dangerous and over the maximum tolerable limit.

When this happens, the LED just lights up, an LDR positioned and enclosed in front of the LED instantly drops its resistance in response to the illumination generated by the LDR.

The sudden reduction in the resistance of the LDR, switches ON T1 which in turn switches ON T2 and the relay, initiating the latching effect of the circuit and the relay.

The load or the appliance at the output is thus immediately switched off when an overload situation is detected.

The whole action takes place within a fraction of a second, giving no chance for any untoward consequence and the whole system is safeguarded by the inclusion of this simple AC mains overload protection circuit.

Formula for Calculating Current limiting Resistor

R1 = 1.5 / I(intended current limit),

For example if I =15 amps, then R1 = 1.5/15 = 0.1 Ohms, and it's wattage will be 1.5 x 15 = 22.5 watts

Mains AC Overload protection Circuit for Voltage Stabilizers
caution electricity can be dangerous

Parts List

  • All resistors are 1/4 watt 5% except R1 (see text)
  • R4 = 56 ohms
  • R4, R7 = 1K
  • R5 = 10K
  • R6 = 47K
  • P1 = 100K preset
  • Diodes = All are 1N4007
  • T1 = BC547
  • T2 = BC557
  • C2 = 10uF/25V
  • LD1 = red LED 20 mA
  • Relay = 12 V/200mA 30 amps

The LED/LDR device can be assembled manually as per the following example image

You'll also like:

  • 1.  Home EMF Radiation Protector Neutralizer Circuit
  • 2.  How to Select MOV – Explained with a Practical Design
  • 3.  Automatic Voltage Regulator (AVR) Analyzer
  • 4.  Rat Repellent Circuit Diagram
  • 5.  5 KVA to 10 KVA Automatic Voltage Stabilizer – 220 Volts, 120 Volts
  • 6.  SMPS Voltage Stabilizer Circuit

About Swagatam

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials.
If you have any circuit related query, you may interact through comments, I'll be most happy to help!

Have Questions? Please Comment below to Solve your Queries! Comments must be Related to the above Topic!!

Subscribe
Notify of
82 Comments
Newest
Oldest
Inline Feedbacks
View all comments

Primary Sidebar

Categories

  • 3-Phase Power (15)
  • 324 IC Circuits (19)
  • 4017 IC Circuits (52)
  • 4060 IC Circuits (26)
  • 555 IC Circuits (99)
  • 741 IC Circuits (20)
  • Arduino Engineering Projects (83)
  • Audio and Amplifier Projects (115)
  • Battery Chargers (83)
  • Car and Motorcycle (95)
  • Datasheets (74)
  • Decorative Lighting (Diwali, Christmas) (33)
  • Electronic Components (101)
  • Electronic Devices and Circuit Theory (36)
  • Electronics Tutorial (120)
  • Fish Aquarium (5)
  • Free Energy (34)
  • Fun Projects (13)
  • GSM Projects (9)
  • Health Related (20)
  • Heater Controllers (29)
  • Home Electrical Circuits (104)
  • How to Articles (20)
  • Incubator Related (6)
  • Industrial Electronics (28)
  • Infrared (IR) (40)
  • Inverter Circuits (98)
  • Laser Projects (12)
  • LED and Light Effect (93)
  • LM317/LM338 (21)
  • LM3915 IC (25)
  • Meters and Testers (66)
  • Mini Projects (150)
  • Motor Controller (67)
  • MPPT (7)
  • Oscillator Circuits (26)
  • PIR (Passive Infrared) (8)
  • Power Electronics (34)
  • Power Supply Circuits (79)
  • Radio Circuits (10)
  • Remote Control (48)
  • Security and Alarm (62)
  • Sensors and Detectors (121)
  • SG3525 IC (5)
  • Simple Circuits (75)
  • SMPS (29)
  • Solar Controllers (61)
  • Timer and Delay Relay (53)
  • TL494 IC (5)
  • Transformerless Power Supply (8)
  • Transmitter Circuits (41)
  • Ultrasonic Projects (16)
  • Water Level Controller (45)

Calculators

  • AWG to Millimeter Converter
  • Battery Back up Time Calculator
  • Capacitance Reactance Calculator
  • IC 555 Astable Calculator
  • IC 555 Monostable Calculator
  • Inductance Calculator
  • LC Resonance Calculator
  • LM317, LM338, LM396 Calculator
  • Ohm’s Law Calculator
  • Phase Angle Phase Shift Calculator
  • Power Factor (PF) Calculator
  • Reactance Calculator
  • Small Signal Transistor(BJT) and Diode Quick Datasheet
  • Transistor Astable Calculator
  • Transistor base Resistor Calculator
  • Voltage Divider Calculator
  • Wire Current Calculator
  • Zener Diode Calculator

© 2023 · Swagatam Innovations

wpDiscuz