Insights · Chandigarh tricity
Dry-type transformer or compact substation for a tricity building?
Published 4 November 2026 by Jaybee Industries, Panchkula Customer Connect
Ask tricity consultants about the electrical side of a new building and one question comes up again and again: should the transformer go inside the building as a dry-type unit, or outside as a compact substation? The two aren't really competitors, because they solve different problems. This guide explains where each one fits.
What each option is
A dry-type transformer (cast resin or VPI) uses air and solid insulation instead of oil. With no oil to leak or catch fire, it can sit in a basement electrical room near the load. A compact substation (CSS) is a factory-assembled package with HV switchgear, a transformer (usually oil-filled) and the LV panel in one weatherproof enclosure, normally placed outdoors.
Side-by-side
| Question | Dry-type | Compact substation |
|---|---|---|
| Where does it go? | Inside the building, close to the load | Outside, on a small plinth |
| Fire and oil concerns | No oil, so suited to occupied spaces | Oil-filled unit sealed in an outdoor enclosure |
| Space | Needs a ventilated electrical room | Saves building space, needs ground area |
| Site work | HV and LV panels are separate items | One pre-wired package, so fewer interfaces |
| Typical tricity use | Hospitals, offices, malls, hotels | Group housing, commercial strips, campuses |
When dry-type is usually the answer
Choose dry-type when the substation must be inside or under an occupied building, when the fire officer or consultant won't allow oil indoors, or when long LV cable runs from an outside yard would add losses and cost. Hospitals in Chandigarh and Mohali and multi-storey offices are typical cases. See oil vs dry-type for more.
When a compact substation is usually the answer
A CSS usually makes sense when the plot has a corner of open ground, when you want the HV equipment out of the building, or when the project is phased and each phase can get its own package. Zirakpur and Kharar housing projects often fit this pattern. See compact substations explained.
Questions to settle before you ask for quotes
- What is the diversified load per block or phase?
- Is there a ventilated room of the right size, or only open ground?
- What does the utility require at the HV interface?
- Who will maintain it, and is an AMC wanted?
Jaybee makes both: cast resin and VPI dry-type from about 16 kVA to 5 MVA, and compact substations. The tricity team can compare the two for your drawings.