Power Transformer Manufacturer for Hospitals: Dry-Type Transformer Selection for Healthcare Facilities

Hospitals and healthcare facilities place very different demands on an electrical distribution system than ordinary commercial buildings.

A hospital may need to supply operating rooms, intensive care areas, diagnostic imaging equipment, laboratories, ventilation systems, chilled-water equipment, pumps, elevators, medical gas systems, IT equipment, UPS systems, and many other loads at the same time. Some operate continuously, while others have large short-term or fluctuating power demands.

This makes transformer selection more than a question of choosing the right kVA rating.

For many healthcare projects, dry-type transformers are a practical choice for indoor distribution because they do not use insulating oil and can be installed in dedicated electrical rooms relatively close to major load centers. However, that does not mean every transformer in a hospital needs to be dry type.

A large healthcare campus may use an outdoor oil-immersed power transformer at the main substation while using dry-type transformers inside individual buildings.

As a power transformer manufacturer, we look at where each transformer will be installed, what it will supply, and how it fits into the complete hospital distribution system before confirming the transformer configuration.

Why Are Hospital Transformer Requirements Different?

Hospitals contain a wide mix of electrical loads.

Typical loads may include:

• medical imaging equipment;
• operating room equipment;
• laboratory systems;
• HVAC and ventilation;
• chillers and cooling systems;
• water pumps;
• elevators;
• sterilization equipment;
• medical gas systems;
• kitchen and laundry equipment;
• UPS systems;
• servers and communication equipment;
• lighting and general building loads.

These loads do not operate in the same way.

Ventilation and cooling may run for long periods. Pumps and motors introduce starting current. Imaging equipment can create high intermittent demand. UPS systems, variable-frequency drives, and electronic power supplies add nonlinear loads to the system.

Because of this, a hospital transformer should be selected around the actual load profile rather than simply adding together every connected load.

Capacity matters, but so do impedance, losses, temperature rise, harmonics, sound level, cooling, enclosure design, installation space, and future expansion.

Where Do Dry-Type Transformers Fit in a Hospital?

Dry-type transformers are particularly suitable where voltage transformation needs to take place indoors.

Common locations can include:

• indoor substations;
• basement electrical rooms;
• electrical rooms on large hospital campuses;
• outpatient buildings;
• laboratory buildings;
• diagnostic centers;
• administrative buildings;
• mechanical and utility buildings;
• distribution points close to major load centers.

Because the transformer does not contain insulating oil, there is no transformer oil to contain or manage inside the building. This can make dry-type construction practical where installation space, fire protection planning, building layout, and indoor operation are important considerations.

The transformer still needs a suitable electrical room.

Ventilation, access, clearance, noise, cable routing, enclosure protection, and maintenance space all need to be considered before the transformer dimensions and arrangement are finalized.

Dry-Type Transformers Can Bring Transformation Closer to the Load

In a large hospital, carrying very high low-voltage current over long distances can require large cables or busduct systems.

One possible distribution arrangement is:

Utility supply → Main substation → Medium-voltage distribution → Indoor dry-type transformer → Low-voltage switchboard → Hospital loads

Instead of transforming all power to low voltage at one distant point, medium voltage can be distributed closer to individual buildings or major load areas before being stepped down.

This can be useful in large hospitals and medical campuses with several buildings.

For example, an inpatient building, outpatient center, laboratory, and mechanical services building may each have their own distribution transformer rather than depending on one large low-voltage distribution point.

The exact arrangement should follow the hospital’s electrical design, but transformer location has a direct effect on cable length, current level, installation space, and future expansion.

Does Every Hospital Transformer Need to Be Dry Type?

No.

Dry-type and oil-immersed transformers can both have a place in the same healthcare project.

For example, a large hospital campus may use:

Grid supply → Outdoor oil-immersed power transformer → Medium-voltage distribution → Indoor dry-type transformers → Building distribution

The outdoor transformer handles the main voltage transformation, while smaller indoor transformers serve individual buildings or load areas.

In another project, the incoming utility voltage may already be suitable for direct distribution to indoor transformer rooms.

The right arrangement depends on:

• incoming voltage;
• required transformer capacity;
• indoor or outdoor installation;
• available electrical room space;
• fire protection requirements;
• distribution distance;
• load arrangement;
• local standards;
• future expansion plans.

So the important question is not whether a hospital should use dry-type transformers everywhere.

The better question is where the voltage transformation takes place and what conditions exist at that location.

Transformer Capacity Should Follow the Real Hospital Load

Hospital transformer sizing should be based on realistic operating demand.

Simply adding every connected load together can produce an unnecessarily large transformer, while using only an estimated average load can leave too little capacity during periods of high demand.

The load study normally needs to consider:

• continuous loads;
• peak simultaneous demand;
• HVAC and ventilation;
• cooling equipment;
• pumps and motors;
• medical imaging;
• laboratories;
• elevators;
• UPS systems;
• IT equipment;
• kitchen and laundry loads;
• standby or emergency distribution;
• planned future expansion.

The operating schedule also matters.

Hospitals normally operate around the clock, so some transformer loads remain relatively steady throughout the day and night. Others vary according to patient activity, weather conditions, equipment schedules, and building occupancy.

This is different from an office building that may become lightly loaded overnight.

When we review a hospital power transformer requirement, we therefore want to understand both the peak demand and the loads that remain connected for long periods.

Medical Imaging Equipment Needs to Be Considered Separately

Diagnostic equipment can have a noticeable effect on local transformer loading.

Depending on the healthcare facility, this may include:

• CT systems;
• X-ray equipment;
• MRI support equipment;
• fluoroscopy equipment;
• mammography systems;
• other diagnostic equipment.

These systems do not necessarily operate at their maximum electrical demand continuously.

Some have high short-duration demand, while their cooling and auxiliary systems may operate for much longer.

For this reason, the presence of imaging equipment does not automatically mean that a much larger transformer is required.

We prefer to review the actual equipment information, including:

• rated input;
• maximum demand;
• operating cycle;
• starting or inrush characteristics where relevant;
• power factor;
• associated cooling equipment;
• other loads connected to the same transformer.

This gives a much better basis for transformer sizing than applying a fixed margin simply because the project includes imaging equipment.

UPS and VFD Loads Can Affect Transformer Heating

Hospitals use a large amount of power electronics.

UPS systems support critical electrical loads, while VFDs are commonly used with pumps, fans, cooling systems, and other mechanical equipment. Electronic medical equipment, computers, LED lighting, and switching power supplies can add further nonlinear loads.

These loads can introduce harmonic currents into the electrical system.

If the nonlinear load percentage is significant, the transformer should be evaluated accordingly.

Useful information includes:

• total UPS capacity;
• expected UPS loading;
• VFD quantity and rating;
• proportion of nonlinear load;
• harmonic data when available;
• continuous transformer loading;
• neutral loading;
• required temperature rise.

The solution should not automatically be to increase transformer capacity.

Depending on the actual electrical conditions, winding design, conductor sizing, thermal margin, loss performance, and transformer rating all need to be considered together.

This is why providing the load schedule and major equipment information early helps us make a more suitable transformer proposal.

Noise Needs More Attention for Indoor Hospital Transformers

Noise is an important consideration whenever a transformer is installed inside a hospital building.

Patient rooms, consulting rooms, offices, laboratories, and treatment areas may be located close to electrical rooms. Even when the transformer operates normally, unwanted sound transmission can become a building-design issue.

The transformer sound requirement should therefore be discussed together with the installation location.

Important points include:

• required transformer sound level;
• distance from occupied rooms;
• transformer-room wall construction;
• ventilation openings;
• mounting arrangement;
• enclosure structure;
• nearby mechanical equipment.

Transformer noise also cannot be considered separately from the building.

A low-noise transformer installed in a poorly designed room may still transmit sound through floors, walls, ducts, or structural connections.

If the transformer room is close to sensitive areas, tell us during the specification stage so that the sound requirement can be included before production.

Dry-Type Transformer Rooms Still Need Proper Ventilation

Dry-type does not mean heat-free.

Every transformer produces losses during operation, and those losses become heat inside the electrical room.

This can become particularly important in:

• basement transformer rooms;
• compact indoor substations;
• rooms with limited natural ventilation;
• hot climates;
• installations with several transformers in one room.

If heat cannot be removed effectively, the ambient temperature around the transformer rises.

That reduces the thermal margin available to the transformer and can affect long-term operation.

Before confirming a dry-type transformer, it is useful to know whether the electrical room uses:

• natural ventilation;
• forced ventilation;
• air conditioning;
• dedicated exhaust;
• natural-air transformer cooling;
• forced-air transformer cooling.

Clearance around the transformer also matters.

Placing the enclosure too close to a wall or blocking ventilation openings can restrict airflow even when the transformer itself is correctly rated.

For this reason, transformer size, enclosure, ventilation, and room layout should be coordinated rather than handled separately.

Impedance Needs to Match the Hospital Distribution System

Transformer impedance affects both voltage behavior and short-circuit current.

A lower impedance is not automatically better.

If transformer impedance is too low, prospective short-circuit current on the secondary side may increase. This can affect:

• low-voltage switchgear ratings;
• busbar design;
• circuit breaker selection;
• protection coordination.

If impedance is too high, voltage drop can become more noticeable under heavy load or during motor starting.

The specified impedance therefore needs to work with the complete hospital electrical design.

For a hospital project, we normally want to know:

• upstream fault level;
• required transformer impedance;
• downstream switchgear rating;
• motor starting requirements;
• voltage-drop limits;
• cable or busduct arrangement;
• protection settings;
• whether transformers will operate in parallel.

If the electrical consultant has already completed a short-circuit study, the specified transformer impedance should be included in the inquiry.

Parallel Transformers Need to Be Confirmed Before Manufacturing

Larger hospitals sometimes use two or more transformers for load division, operational flexibility, or future expansion.

If transformers are expected to operate in parallel, this needs to be clear from the beginning.

Parallel operation requires compatible electrical characteristics.

These include:

• voltage ratio;
• vector group;
• phase sequence;
• impedance;
• tap position;
• frequency;
• secondary voltage.

Two transformers with the same capacity are not automatically suitable for parallel operation.

This becomes especially important when adding a new transformer to an existing hospital.

In that situation, send us the existing transformer nameplate, drawings, test report, impedance, vector group, tapping range, and secondary voltage if available.

We can then review the new transformer against the existing unit before manufacturing.

Future Expansion Should Be Considered Without Excessive Oversizing

Hospitals often expand in stages.

Future work may include:

• new wards;
• additional operating rooms;
• diagnostic departments;
• laboratory expansion;
• outpatient buildings;
• larger HVAC systems;
• additional IT equipment;
• EV charging;
• new support facilities.

Known expansion should be included in the electrical plan, but this does not mean every transformer needs to be heavily oversized from the beginning.

If a new wing is already planned and its expected load is reasonably clear, capacity can be reserved for it.

If expansion is only a long-term possibility, the distribution system can sometimes be arranged so that an additional transformer can be installed later.

For a large hospital campus, several appropriately located transformers may provide more practical expansion options than putting all expected future capacity into one very large transformer.

This depends on the site layout and electrical distribution strategy, so it is worth discussing future stages when the transformer arrangement is first developed.

Emergency Power Needs to Be Considered as Part of the Complete System

Hospitals place strong emphasis on power continuity, but the transformer is only one part of that system.

Depending on the project, the electrical system may include:

• utility supplies;
• generators;
• automatic transfer switches;
• UPS systems;
• battery systems;
• medium-voltage switchgear;
• low-voltage switchboards;
• normal distribution;
• emergency distribution.

The transformer has to fit this architecture.

For example, a transformer downstream of an emergency generator may supply a different load group from the normal utility transformer.

In another arrangement, the same transformer may remain part of the distribution path while the upstream source changes between utility and standby generation.

These arrangements affect transformer loading and sometimes operating conditions.

When emergency and normal systems are separated, tell us which loads each transformer serves so that the rating can be reviewed against the correct operating condition.

The final system also needs to comply with the healthcare electrical requirements and codes applicable to the project location.

The Enclosure Should Match the Transformer Room

An indoor transformer still needs appropriate protection from its environment.

The enclosure should be selected according to the actual electrical room rather than choosing an IP rating without considering the installation.

Important conditions can include:

• dust;
• moisture;
• ventilation;
• restricted access;
• cable entry;
• busbar connection;
• maintenance clearance;
• surrounding equipment.

The enclosure also affects airflow around the transformer.

A more enclosed structure may require different consideration of ventilation and heat dissipation than an open indoor arrangement.

This is why we prefer to confirm the enclosure before the final transformer layout is completed.

Cable entry direction and terminal arrangement should also be confirmed early, especially in hospital electrical rooms where space may be limited and switchgear, busduct, and cable trenches have already been designed.

What Information Should You Send Us for a Hospital Transformer Project?

The more complete the electrical information is at the beginning, the easier it is to match the transformer to the actual healthcare project.

The main information normally includes:

A single-line diagram is particularly useful.

It allows us to see where the transformer sits between the utility supply, switchgear, generators, UPS systems, distribution boards, and hospital loads.

A load schedule is also helpful when several different types of equipment share the same transformer.

Dry-Type Transformer Design Starts With the Installation Conditions

Once the electrical data is confirmed, the transformer can be designed around the actual operating conditions.

For a cast-resin dry-type transformer, the design needs to consider:

• winding current density;
• insulation system;
• conductor selection;
• temperature rise;
• short-circuit strength;
• core losses;
• load losses;
• impedance;
• cooling;
• enclosure;
• terminals;
• temperature monitoring;
• required accessories.

Manufacturing and testing then need to follow the approved transformer specification.

At HONLE, we supply dry-type transformers for indoor distribution as well as oil-immersed transformers for applications where liquid-filled construction is more suitable.

This gives us more flexibility when a hospital project contains several transformer locations.

We do not need to force the same transformer construction into every part of the site.

HONLE Can Match Different Transformer Locations Within One Healthcare Project

A hospital campus may contain several very different transformer requirements.

The main outdoor substation may need a larger oil-immersed power transformer.

An inpatient building may need an indoor dry-type transformer.

A laboratory or outpatient building may have another transformer with a different load profile.

A mechanical services building may supply large motors, pumps, and cooling equipment.

These transformers do not have to share exactly the same capacity, impedance, enclosure, or cooling arrangement.

What matters is that each unit matches its own location and duty while remaining compatible with the overall electrical system.

When you send us a healthcare transformer project, we can review:

• transformer type;
• rated capacity;
• voltage ratio;
• impedance;
• load characteristics;
• installation location;
• ambient temperature;
• altitude;
• harmonic conditions;
• cooling;
• enclosure;
• sound requirements;
• terminal arrangement;
• accessories;
• testing requirements.

If the project includes both indoor and outdoor substations, we can also review the dry-type and oil-immersed transformer requirements together.

Conclusion

Dry-type transformers fit naturally into many hospital and healthcare distribution systems, especially where voltage transformation takes place inside the building.

Their oil-free construction makes them practical for indoor electrical rooms, but choosing a dry-type transformer is only the beginning.

The transformer still needs to match the hospital’s capacity, load profile, UPS and VFD loads, harmonic conditions, impedance, ventilation, noise requirements, enclosure, installation space, and future expansion.

Not every transformer on the site needs to use the same construction.

A large hospital campus may use an outdoor oil-immersed power transformer for the main substation and dry-type transformers for indoor distribution closer to individual buildings and major load centers.

As a power transformer manufacturer, we can work from your single-line diagram, load schedule, transformer specification, and installation conditions to determine which transformer arrangement fits each part of the healthcare facility.

The more clearly the electrical system is defined at the beginning, the easier it is to manufacture a transformer that fits the real project rather than relying on a standard configuration.

Frequently Asked Questions

Are dry-type transformers suitable for hospitals?

Yes. They are commonly used for indoor distribution where oil-free construction, indoor installation, space planning, and building fire protection are important considerations.

Does every transformer in a hospital need to be dry type?

No. Outdoor substations may use oil-immersed transformers, while dry-type transformers are used for indoor distribution. Both types can be used within the same hospital campus.

Can a dry-type transformer supply imaging equipment?

Yes, provided its capacity and electrical characteristics are matched to the actual equipment demand, operating cycle, and other loads connected to the transformer.

Do UPS systems affect transformer selection?

They can. Large UPS and other nonlinear loads may introduce harmonic currents, so their capacity and loading characteristics should be included when specifying the transformer.

Is a larger transformer always safer for a hospital?

No. Capacity should be based on realistic peak demand, continuous load, operating conditions, and confirmed future expansion rather than simply choosing the largest practical rating.

Can two hospital transformers operate in parallel?

Yes, but voltage ratio, vector group, impedance, tap position, and other electrical characteristics need to be compatible before parallel operation is planned.

What should we send HONLE for a hospital transformer quotation?

Send the required capacity, primary and secondary voltage, impedance, vector group, installation location, major loads, ambient conditions, enclosure requirements, applicable standards, and preferably the project single-line diagram and load schedule.