Key Factors to Consider When Choosing a Variable Transformer
Selecting the right variable transformer is essential to ensure safe, efficient, and precise control of your electrical equipment. With various models and specifications available—from compact bench units to high-capacity industrial transformers—understanding the core selection criteria will help you make an informed decision.
Input and Output Voltage
Most variable transformers stocked by Lyons Instruments operate with a standard UK mains input of either 230V or 240V. However, output voltage ranges vary depending on the model and are a critical factor in your selection.
Common output voltage ranges include:
- 0–115% of input (common in Portavolt models)
- 0–240V or 0–275V (seen in many Regavolt models)
- 0–100% or 0–113% for precision control
Current Rating (Amperes)
The current rating, measured in amperes (A), determines how much load the transformer can handle. Choosing a transformer with insufficient current capacity may lead to overheating, voltage drop, or equipment failure.
Always calculate the maximum current your equipment will draw and choose a transformer with at least 10–20% overhead for safe operation.
Power Rating (VA or kVA)
The power rating defines the total load capacity of the transformer and is usually expressed in Volt-Amperes (VA) or kilovolt-amperes (kVA). VA ratings are ideal for smaller, lower-load applications (e.g., 160VA, 500VA). kVA ratings (1kVA, 10kVA, 12kVA) are suitable for high-power environments such as manufacturing, HVAC systems, or lab-scale industrial simulations.
Example:
A 230V, 10A model would be rated around 2.3kVA.
Choose a power rating that reflects your application’s load while allowing headroom for performance and longevity.
Output Control and Metering Options
Many Lyons Instruments variable transformers are available with analogue or digital meters, while some models come without metering for basic control.
Analogue Meters: Classic needle displays; useful for educational or visual monitoring.
Digital Meters: Offer greater precision and readability; ideal for lab work and professional testing.
No Meter Models: More compact and economical for basic applications.
Enclosure Type and Build Quality
Safety and durability are key, especially in professional or educational environments. Enclosed models offer protective housings that shield the transformer from dust, moisture, and accidental contact—meeting key electrical safety standards in the UK.
Enclosed Transformers: Best for industrial labs, workshops, and schools (e.g. Regavolt 715-ED, Portavolt with meters)
Open-Frame Transformers: Suitable for internal installations or OEM integration, where the unit is housed within larger equipment.
Match the Transformer to Your Environment
When choosing a variable transformer, consider the installation environment, required voltage control, equipment load, and the need for monitoring and safety. Lyons Instruments provides one of the UK’s most comprehensive ranges, supporting everyone from universities to heavy industry with expert guidance and dependable solutions.
