Control transformers play a critical role in delivering stable, reliable power to control circuits. When they’re sized incorrectly, you can end up with nuisance trips, overheated components, voltage drops, and unexpected downtime — all issues that can be avoided with proper transformer selection.

Here are the five most common control transformer sizing mistakes we see in the field, and how Micron helps prevent them.

Industrial Control Transformer: IMPERVITRAN

Micron’s fully encapsulated ImperviTRAN industrial control transformer is the most accepted transformer in the industry. Its clean design and toughness make it a favorite of industrial and commercial equipment manufacturers.

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1. Undersizing the VA Rating

One of the most frequent mistakes is choosing a transformer with too low of a VA rating for the connected load. When the VA rating is undersized, the transformer struggles to supply enough power, leading to:

Voltage dips
Overheating
Reduced lifespan
Intermittent control failures

Micron offers a wide range of VA ratings to match everything from small control circuits to heavy industrial loads.

2. Ignoring Inrush Current

Devices like contactors, solenoids, and relays can draw significant inrush current when energized. If the transformer isn’t sized to handle that momentary surge, you may see:

Flickering control voltage
Tripped breakers
Failed startups

Micron’s control transformers are designed with high inrush capability, ensuring stable performance even with demanding loads.

3. Not Accounting for Ambient Temperature

Transformers installed in hot environments — inside panels, near motors, or in poorly ventilated areas — may not deliver their full rated output. High ambient temperatures can cause:

Reduced VA capacity
Thermal stress
Premature failure

Micron provides clear derating guidelines so you can size correctly based on real‑world conditions.

4. Using the Wrong Primary Voltage Configuration

Many facilities operate with multiple voltage systems (480V, 240V, 208V, etc.). Selecting a transformer with the wrong primary voltage configuration can lead to:

Incorrect output voltage
Overheating
Damaged control components

Micron’s multi‑tap primary designs make it easy to match your facility’s voltage without guesswork.

5. Forgetting About Future Expansion

A transformer sized “just enough” for today’s load may not support tomorrow’s upgrades. Adding even a small device — a relay, indicator light, or sensor — can push an undersized transformer past its limit.

Micron’s control transformers offer flexible sizing options so you can plan for growth without overspending.

Why Micron Is the Go‑To Choice for Control Power

Micron has been a trusted name in control transformers for decades. Their products are known for:

High inrush capability
Reliable voltage regulation
Durable construction
Wide VA range
Flexible primary/secondary configurations

Whether you’re building a new panel or upgrading an existing system, Micron delivers dependable control power you can count on.

Need Help Sizing the Right Transformer?

Send us your control power requirements — WD Engineering Sales will help you select the correct Micron transformer for your application.

We support engineers across Iowa, Illinois, Kansas, Missouri, Nebraska, and Wisconsin with product guidance, sizing help, and technical resources.

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Micron: 5 Control Transformer Sizing Mistakes (And How to Avoid Them)