ABB ReliaGear General Purpose Transformers and Small Power Transformers are both low-voltage dry-type units. General Purpose transformers are suitable for a broad range of distribution applications, including residential, commercial and industrial power distribution, and are available with either aluminium or copper windings.
ABB Small Power Transformers, including the control transformer subcategory, cover a narrower range, used to supply individual control cabinets, panels, machinery and devices. These compact, single-phase units are rated 50 VA - 3000 VA and support input voltages up to 600 V.
ABB Canada has two primary lines of low-voltage dry-type transformers: General Purpose Transformers and Small Power Transformers. These two categories are easily confused; each is built to serve different application needs. Understanding the difference between their intended uses, along with their electrical ratings and construction, helps specify the correct transformer for the job.
Control Power Transformers sit within ABB’s broader Small Power Transformer range. Because the range includes different transformer types for different load requirements, the specific model should be matched to the application
ABB also has a third line, known as K-Factor Transformers. These are specialized units, built specifically for harmonic-rich, non-linear loads.
Key Takeaways
- ABB ReliaGear General Purpose Transformers have a 10 kV BIL rating, available with either aluminium or copper windings. They come with a NEMA 2 enclosure as standard, upgradable to NEMA 3R by requesting a supplementary rain shield kit.
- ABB Small Power Transformers are single phase units using only copper windings. They are rated from 50 VA - 3000 VA for input voltages up to 600 V. This makes them suitable for applications including control cabinets and panels, and circuits requiring with high inrush currents such as conveyor and amusement ride supplies.
- Where harmonic-rich non-linear loads are of concern, ABB's K-Factor range is the appropriate product family.
- Control transformers sit within ABB’s Small Power Transformer offering. Specific models should be selected according to the control circuit’s voltage, steady-state VA and inrush VA requirements. Links to the relevant control power transformer buylog and technical guide can be found on our Small Power Transformer page
What Is a General Purpose Transformer?
A general purpose transformer, such as ABB's ReliaGear QL and QF dry-type range, is designed for residential, commercial and industrial power-distribution applications. They step voltages up or down in order to supply things like lighting and heating systems, along with motorized machine and appliances, with the appropriate power loads.
The ReliaGear QL and QF dry-type range is available with either aluminum or copper windings, carries 10 kV BIL and 40°C ambient ratings within a 220°C insulation system. Units ship with a NEMA 2 drip-proof enclosure as standard, with an optional rain shield kit available to convert the enclosure to NEMA 3R for outdoor installations. Selected units up to 150 kVA also include a lug kit and ground bar kit.
Each unit undergoes thorough factory testing for shorts and coil integrity, current and loss, voltage, impedance and noise, and is cUL listed to CSA 802.2 and NRCan requirements.
Typical general purpose transformer applications
General purpose transformers can be used across a wide range of residential, commercial and industrial applications and are not bound to specific roles. In practice, that spans everything from residential utility connections to commercial lighting and HVAC systems, or industrial areas that need dependable, code-compliant distribution across shop and factory floors.
What Is a Small Power Transformer, and How Does It Relate to a Control Transformer?
ABB's Small Power Transformers also known as control transformers are compact, single-phase dry-type transformers designed to provide regulated voltage for space-constrained installations. Supporting input voltages up to 600 V with a capacity range spanning 50 VA - 3000 VA, they are typically used in control cabinets and industrial control panels rated to UL 508. Circuits that require high inrush current, including applications involving conveyors and amusement park equipment, also use Small Power Transformers.
ABB Small Power Transformers use copper windings around a welded steel core, with various winding temperature-rise options available. They feature IP20 finger-safe terminals and encapsulated coils to help reduce corrosion and noise, with fuse-block kit accessories also available. Most units operate at 60 Hz, with some 50/60 Hz models available for dual-frequency applications.
Where are small power and control transformers used?
ABB Small Power Transformers are used in applications that require regulated voltage in a compact space. Typical uses include control cabinets, industrial control panels, OEM equipment, machinery, conveyors and amusement park equipment. Some applications within the Small Power range also need to accommodate high inrush current.
Within this range, the exact transformer type depends on the load. Control Power Transformers are suited to applications such as HVAC systems, signal and alarm systems, industrial control panels, lighting and circuit isolation.
General Purpose vs Small Power Transformers: Key Differences at a Glance
The practical distinction between a General Purpose and a Small Power transformer comes down to specifications and the intended application. Where General Purpose Transformers support a broad range of commercial, residential, and industrial applications, Small Power Transformers are for single-phase, space-constrained installations, such as control cabinets and industrial panels, supply loads to machinery and similar equipment.
Specification | ABB General Purpose Transformers | ABB Small Power Transformers |
ABB product/category | ReliaGear QL & QF General Purpose | Small Power, including Control Power transformers |
Winding material | Aluminium or copper | Copper |
Phase | Three-phase models available | Single phase |
Capacity | 15–500 kVA, with 750 kVA available | 50 VA - 3000 VA |
Input voltage | Model-dependent | Up to 600 V |
Insulation | 220°C insulation system | 180°C NEMA/UL insulation temperature class; IEC 60085 A, F or H |
Enclosure / terminals | NEMA 2 standard; NEMA 3R via rain shield kit | IP20 finger-safe terminals; encapsulated coils |
Certifications | cUL listed (CSA 802.2 / NRCan) | UL & cUL listed under ABB’s stated XPTQ files |
Applications | Residential, commercial and industrial power distribution | Equipment manufacturers, control cabinets, conveyors, amusement parks, industrial control panels and high-inrush circuits |
While selecting any transformer requires careful specification, there are a number of differentiators that quickly steer decisions. Winding material is one. General Purpose Transformers offer a choice of aluminium or copper, while Small Power Transformers are only available with copper windings.
Likewise, whether a transformer supports three-phase or only single-phase configurations will narrow down options. Capacity ratings also directly reflect how suitable a transformer is for a given application. Small Power Transformers are rated for 50 VA - 3000 VA range, appropriate for supplying individual cabinets, panels and machinery.
General Purpose Transformers, by contrast, have much larger capacity ratings, allowing them to serve a far broader range and scale of applications.
How to Choose Between General Purpose and Small Power Transformers
Use the following guide alongside the comparison table to help narrow down the appropriate transformer for an application.
Application
Use General Purpose Transformers where the unit’s specifications suit residential, commercial or industrial power-distribution requirements.
Consider Small Power Transformers where regulated voltage is required for compact control, machine or panel applications.
Size and installation environment
Small Power Transformers are designed for applications where compact size is important, including control cabinets and industrial control panels.
General Purpose Transformers come with a NEMA 2 enclosure as standard, with rain shield kits available to convert compatible units to NEMA 3R for outdoor installations. Installation space and enclosure requirements should therefore be considered when selecting between the two ranges.
Phase and rating
Check the phase, voltage and kVA requirements of the application.
ABB Small Power Transformers are single-phase units with a capacity range of 50 VA - 3000 VA and input voltages up to 600 V.
ABB General Purpose Transformers are available in three-phase configurations and across substantially higher kVA ratings, with available voltage combinations depending on the specific model.
Control and inrush applications
Control cabinets, industrial control panels, equipment manufacturers, and circuits requiring high inrush current are all listed applications for ABB Small Power Transformers.
Within the Small Power range, Control Power Transformers serve different application requirements. Control Power Transformers are intended for applications such as HVAC, signal and alarm systems, industrial control panels, lighting and circuit isolation.
Select the specific transformer according to the voltage, kVA, regulation and inrush requirements of the circuit.
When K-Factor is the more relevant requirement
Sometimes loads are harmonic-rich and non-linear. When this is the case, it often requires a different type of transformer. ABB’s K-Factor range is built to perform reliably in these kinds of environments. Available in two models, K4 for moderate harmonics, and K13 for high levels (up to 100% harmonics), they support an apparent power range of 15 to 300 kVA and feature a 200% rated neutral with full-width copper electrostatic shielding. Some ABB General Purpose Transformer models also feature K-Factor ratings as an available option.
Choosing Between General Purpose and Small Power Transformers
Selecting the correct low-voltage dry-type transformer can seem confusing at first, but with the right approach and attention to a project’s specification needs, the correct choice readily becomes apparent. Applications serve as a great rule of thumb:
For single-phase installations with tight space constraints, such as control cabinets and control panels, Small Power Transformers are likely the appropriate choice. When you’re specifying for broader industrial, commercial, or residential projects that require three-phase configurations, a General Purpose Transformer is probably correct.
K-Factor requirements should also be considered when harmonic-rich, non-linear loads are present, requiring a different family of transformers.
If you have any questions about General Purpose or Small Power Transformers:
Frequently Asked Questions
What is an ABB Small Power Transformer used for?
ABB Small Power Transformers are used where regulated voltage is needed in a compact installation. Typical applications include control cabinets, UL 508 industrial control panels, equipment manufacturing, conveyors, amusement park equipment and circuits that experience high inrush current.
ABB Small Power Transformers are single-phase units rated from 50 VA - 3000 VA, with input voltages up to 600 V.
What is the difference between a General Purpose Transformer and a Small Power Transformer?
The main differences are their ratings, configuration and intended applications.
ABB Small Power Transformers are compact, single-phase units rated from 50 VA - 3000 VA and use copper windings. They are commonly used in control panels, machinery and other space-constrained applications.
ABB General Purpose Transformers are designed for broader residential, commercial and industrial power-distribution applications. Three-phase models are available, and the range offers both aluminium and copper windings.
General Purpose Transformers also use NEMA 2 enclosures as standard, with rain shield kits available for conversion to NEMA 3R where outdoor installation is required.
Can a Small Power Transformer replace a General Purpose Transformer?
Not automatically. The two ranges are designed for different applications and have different electrical ratings and configurations.
Selection should be based on factors such as voltage, kVA requirement, phase, available installation space, enclosure requirements and the type of load being supplied.
Are ABB Small Power Transformers UL and cUL listed?
Yes. Our Small Power Transformers are UL and cUL listed under XPTQ:E323774, XPTQ2:E323774 and XPTQ7:E323774.
