Ohm’s Law and your compressor: Understanding the electrical connection

A quick introduction to Ohm’s Law

To turn air into compressed air, you need power. This power comes in the form of electricity: Alternating Current or Direct Current.

Ohm’s Law describes how voltage (V), current (I) and resistance (R) behave together in an electrical circuit:

[V = I \times R]

Here’s a simple way to understand each term:

• Voltage — the electrical force that drives power through a circuit
• Current — the movement of electrical energy
• Resistance — the components or conditions that limit that movement

Think of it like air moving through pipework in your compressed air system:

Pressure ≈ voltage, flow ≈ current, restrictions ≈ resistance.

If one part of the process changes, the others will all react, and this will impact the way your compressor operates.

Why this equation matters for air compressors

Electric motors are at the heart of your compressor system, and they rely on a stable electrical supply to run efficiently. When voltage or current falls outside the levels the motor is designed for, performance can quickly decline.

Ohm’s Law helps explain where the issue originates.

1. Detecting hidden motor problems

If the resistance of the windings changes, due to heat, wear or contamination, your compressor’s motor may draw unusually high current.

High current often leads to:

• Overheating
• Insulation breakdown
• Tripped protection devices
• Reduced service life

2. Voltage drop on the supply line

Incorrect cable sizing, loose terminals, or long cable runs can cause your compressor’s motor to receive less voltage than required.

Low voltage forces the motor to pull more current to compensate, which increases strain and heat.

3. Choosing the correct electrical setup

Ohm’s Law comes into play when our service technicians and electrical contractors are:

• Setting up new installations
• Verifying load conditions
• Measuring expected current draw
• Ensuring protective devices are correctly matched

This all helps support efficient compressor operations and reduces the likelihood of interruptions or breakdowns.

This phenomenon is called self-induction. Self-induction in an alternating current unit gives rise in part to phase displacement between the current and the voltage, and in part to an inductive voltage drop. The unit’s resistance to the alternating current becomes apparently greater than that calculated or measured with direct current.

Phase displacement between the current and voltage is represented by the angle φ. Inductive resistance (called reactance) is represented by X. Resistance is represented by R. Apparent resistance in a unit or conductor is represented by Z.