How to specify a transformer enquiry

01 / Describe the electrical system

State the required capacity in kVA or MVA, primary and secondary voltages and operating frequency. Include a single-line diagram when available. Describe the load and any planned expansion instead of supplying a capacity number alone.

Term	Why it belongs in the brief
Vector group	Records winding connection and phase relationship; the project engineer specifies the required arrangement.
Impedance	Part of system fault-level and voltage-regulation assessment; provide the specified value and tolerance.
Taps	Define the voltage adjustment arrangement and required positions.
Losses	Request separately stated no-load and load-loss data at declared reference conditions.
Insulation level	Identify the system insulation requirements in the project specification.

Understand transformer losses

A transformer has losses while energised, even when little load is connected. No-load loss is associated mainly with the magnetic core. Load-dependent losses arise in the windings and other parts and increase as load rises.

Compare the supplier’s declared no-load and load-loss figures at the same reference conditions. Assess them against the expected operating profile: lightly loaded, continuously energised equipment presents a different loss profile from equipment operating near rated load for long periods.

Efficiency is therefore a system and duty question as well as a product-data question. Request the test basis and operating assumptions behind any efficiency figure.

02 / Describe the installation

Location, altitude, ambient conditions and environmental exposure.
Indoor room or outdoor arrangement, enclosure, ventilation and access.
Cable / busbar interfaces and any existing foundation constraints.
Site engineer’s requirements for fire, containment, protection and earthing.
Noise limits, maintenance clearances and lifting access.

03 / Make quotations comparable

Use one requirement schedule for every proposal. Ask each supplier to mark every line as compliant, proposed alternative or excluded, with supporting documents. Separate equipment price, freight, optional testing and site services.

A stated voltage or capacity is not evidence of suitability. Review the proposed model, documents and installation conditions together.

04 / Check applicable obligations

Australia’s Energy Rating program regulates specified distribution transformers. Check the exact product scope and any registration requirements for the proposed model before supply. A general product brochure is not model-specific registration evidence.

Get the transformer enquiry worksheet