Over/under voltage protector

• Main Author: Nah Kien Wah
• Format: Academic Exercise
• Language: English
• Published: 2008
• Subjects: QC Physics
• Online Access: https://eprints.ums.edu.my/id/eprint/20160/1/Overunder%20voltage%20protector.pdf; https://eprints.ums.edu.my/id/eprint/20160/

Over/under voltage protector is designed particularly to overcome the over voltage and under voltage events. It is sensitive enough to disconnect the power supply when the input voltage is out of specific range. Various "over voltage" and "under voltage" is created by using several steps down transformers. Secondary windings of transformers are connected serially, and then its combination voltage measured will be the sum of the output of each transformer. The circuit constructed is connected by the voltage supply which is higher than household power supply (over voltage), hence over voltage range can be determined. While the under voltage range is determined by connecting the voltage supply which is lower than household power supply (under voltage), to the circuit. Operational amplifier IC in the circuit compare its DC voltage with corresponding zener diode, hence control the range of normal power supply permitted in the over/under voltage protector. Over/under voltage protector is built and its range of "voltage permitted" is set to 183.36 V to 262.00 V with uncertainty of 4.61% for over voltage edge and 1.86% for under voltage edge. However, the range of the over voltage and under voltage still can be adjusted using variable resistor VRI and VR2 respectively.