What is the difference between dead-front and live-front transformers?
Dead-front uses separable insulated primary connectors. Live-front uses exposed primary connection surfaces within the compartment. Match the specified construction and the complete termination arrangement, including connector voltage and current ratings.
- Identify the connector interface, manufacturer/type and required voltage class.
- Record the applicable continuous-current and fault-duty requirements.
- Distinguish loadbreak and deadbreak connector configurations; dead-front alone does not establish switching capability.
- Request the primary compartment drawing and cable-interface details, not only a cabinet photograph.
Loop-feed versus radial-feed pad-mounted transformers
Radial feed supplies the unit from a primary path. Loop-feed construction accommodates incoming and outgoing primary cable connections. The project one-line establishes how the system is operated; a loop-feed transformer by itself does not establish two independent supplies, automatic transfer or a redundancy level.
| Field | Question for the equipment offer |
|---|---|
| Front construction | Are the primary connections dead-front or live-front, as required by the specification? |
| Feed arrangement | Does the cable arrangement match the radial or loop one-line? |
| Switching and protection | Which switches, fuses or interrupters are included, and what are their actual duties and ratings? |
| Physical interface | Do bushing locations, cable entry, connector space, secondary terminals and pad openings match the site? |
What drawings should a replacement padmount review include?
Ask for the nameplate, general arrangement, primary and secondary compartment layout, connection diagram and accessory schedule. For an existing installation, include the installed unit's drawings and clear nameplate photographs. Have the project team compare the proposed unit's dimensions and interfaces before accepting a substitution.
- Preserve the full secondary voltage and connection notation, including neutral requirements.
- Identify cable sizes, entry directions, terminal arrangements and enclosure requirements.
- Record any required switches, protection, arresters, gauges and external controls.
- Identify differences between the supplied unit and the controlling specification in writing.
Request a dead-front, live-front, loop-feed or radial-feed padmount
Send Tommy the kVA, primary and secondary voltages, phase, quantity and both front and feed requirements. Include connector and switching details or mark them as open questions. For a bulk order, separate configurations even when their kVA and voltage labels are identical.
Common questions
Written quotes and supporting records control unit-specific ratings, availability, condition, price, and delivery.
Does dead-front mean the transformer is de-energized?
No. It describes the connection construction. Equipment may still be energized; operating and maintenance work follows the site's approved procedures and qualified personnel requirements.
Is every loop-feed transformer dead-front?
Front construction and feed arrangement are separate fields. Confirm both from the specific unit's drawings and specification.
Does loop feed guarantee uninterrupted power?
No. Continuity depends on the complete source, cable, switching, protection and operating arrangement. A loop-feed transformer alone does not establish automatic transfer or project redundancy.