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3-Phase Servo AVR (AC Voltage Stabilizer) — Parts, Tests, Repair & Maintenance

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3-Phase Servo AVR (AC Voltage Stabilizer) — Troubleshooting, Repair & Maintenance By Edwin Ogie • December 18, 2025 • -- AC Voltage Stabilizer — 3-phase servo control type (example from user photo) A practical, step-by-step guide to diagnose, repair and maintain 3-phase servo Automatic Voltage Regulators (AVR) / servo voltage stabilizers. Written in simple terms for technicians and maintenance teams working with generators, UPS rooms and factories. Includes videos, spare-parts list, safety checklist, troubleshooting flow and links to internal/external resources. Contents Why this matters In environments with unstable mains (frequent sags, surges or phase imbalance) a servo AVR protects sensitive equipment by continuously adjusting an autotransformer tap via a small servo motor. A well-maintained stabilizer saves equipment, reduces downtime and prevents costly damage. ...

EQUILIBRIUM OF FORCES

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Equilibrium of Forces — Edwin Ogie Library

Comprehensive e-book: static & dynamic equilibrium, resultant & equilibrant forces, torque, moments, worked examples and a CBT quiz for JSS/Senior students.

Keywords: equilibrium, torque, moments Edwin Ogie Library

Introduction

An object is in equilibrium if it experiences no acceleration — i.e. the net force and net moment acting on it are zero. This e-book covers translational and rotational equilibrium and practical worked examples for classroom and exam preparation.

Equilibrium diagram

Quick links: Edwin Ogie Library (home)CBT Quiz

Forms of Equilibrium

Translational (Linear) Equilibrium

No net force — body at rest or moving with constant velocity (ΣFx = 0, ΣFy = 0).

Rotational Equilibrium

No net torque — sum of clockwise moments = sum of anticlockwise moments (ΣM = 0).

Resultant and Equilibrant Forces

The resultant is the vector sum of all forces. The equilibrant is equal in magnitude but opposite in direction to the resultant.

Parallelogram law  —  R² = P² + Q² + 2PQ cosθ

Example RE1: Two Forces (30 N & 40 N, θ = 60°)

Couples & Torque

A couple is two equal and opposite forces with parallel lines of action but not collinear — producing a pure rotation. Torque (moment) = Force × perpendicular distance (Nm)

Example CT1: Torque

Equilibrium of Three Forces (Triangle of Forces)

If three forces acting at a point keep a body in equilibrium, they can be arranged to form a closed triangle.

Example TF1

Moment of a Force & Principle of Moments

Moment = Force × perpendicular distance

For equilibrium, sum of clockwise moments = sum of anticlockwise moments about any pivot.

Example MM1

Metre Rule Worked Example

Problem (i): A metre rule balances at 48 cm. A 60 g mass is at 6 cm and causes the balance point to shift to 30 cm. Find mass of the rule.

Problem (ii): Move the 60 g mass to 13 cm, find new balance point x (W=80 g).

Additional Worked Examples

EQ1: Beam with two forces

A beam supported at center with 100 N and 150 N at 2 m and 3 m opposite sides — is it in equilibrium?

EQ2: Signboard with two cable tensions (vertical components)

Summary of Key Concepts

  • Equilibrium: No net force and no net moment.
  • Resultant & Equilibrant: Equilibrant balances the resultant.
  • Moment & Torque: Force × perpendicular distance (Nm).
  • Triangle of forces: Three forces in equilibrium form a closed triangle.

30-Question CBT Quiz (15 minutes)

Designed for JSS / early secondary students. Click Start Quiz to begin.

Time Remaining: 15:00
Resources: Edwin Ogie LibraryBibleGateway (for pastoral pieces) • For platform requests see Google/Twitter/Facebook help pages.

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