1000 KVA Pad Mounted Transformers-34.5/0.48 KV | USA 2025

01 General

1.1 Project Description

Solar PV plants don’t really run like your typical industrial loads. Sunlight changes hour by hour, clouds drift in and out, and inverters are often running at partial load – which basically means the 1000 kva pad mounted transformer sees all kinds of intermittent, unpredictable, and sometimes sudden swings.

For this project, we needed to step up 480Y/277 V from the inverter side to 34.5 kV (34500GrdY/19920 V) to feed into the grid. So yeah, this 1000 kVA three-phase pad-mounted transformer is kind of the heart of the system – without it, nothing really moves.

Since it’s outdoors, the design had to hit higher-than-usual standards, and at the same time, we couldn’t compromise on the goals: stable grid connection, flexible voltage regulation, and reliable operation for 20+ years. That’s where Scotech came in. We designed it to tackle multiple challenges at once: keeping operators safe with dead-front construction, making it tough against weather with corrosion-resistant coatings, using FR3 natural ester oil for environmental and fire safety, and laying out everything so inspections and maintenance aren’t a headache.

1.2 Technical Specification

1000kVA three phase pad mounted transformer specification and data sheet

1.3 Drawings

1000KVA three phase pad mounted photovoltaic transformer drawing and nameplate

02 Transformer Design And Performance

2.1 4-Position Loadbreak Switch

This transformer utilizes a 4-position load-break switch, designed for dual-source PV feeder applications. The four positions provide flexible routing and safe loadbreak operation: SOURCE A & B – TAP ON SOURCE A – TAP ON SOURCE B – TAP ON SOURCE A & B – TAP OFF These positions enable safe load-break switching, dual-source selection, and tap-circuit isolation-ideal for PV step-up transformers that require a reliable feeder configuration.

2.2 Insulation & Cooling System

For this 1000 kva pad mounted transformer, we selected FR3 natural ester oil because it provides clear advantages for PV applications. Its high flash point significantly enhances fire safety – a key factor for outdoor installations. FR3 is also biodegradable, supporting environmental compliance requirements. More importantly, it offers excellent thermal performance, allowing the insulation system to handle the cyclical and temperature-driven load variations typical of solar PV sites. The cooling system is KNAN, the natural-ester equivalent of ONAN. For PV applications where loading can vary widely throughout the day, KNAN provides stable and reliable cooling, ensuring consistent performance under fluctuating solar conditions.

2.3 Tank & Safety Design

Since this is a pad-mounted transformer sitting outside, we had to think about safety and durability from every angle. We designed it with dead-front construction – so anyone working near it stays safe – and a loop-feed configuration to make grid connections flexible. The tank and cabinet got a corrosion-resistant, UV-proof coating, because honestly, no one wants a rusty transformer after a year of sun and rain. We also built in measures to prevent theft or accidental tampering. And of course, the FR3 oil doesn’t just help with fire safety – it also keeps the environmental impact low.

03 Terminations And Protection Components

3.1 Bushings & Terminations

HV side (34.5 kV): • 200A Loadbreak / Deadbreak bushings • Lightning arresters • Proper grounding and shielding
	LV side (480V): • 12-hole spade terminals • H0/X0 neutral points brought out separately All components meet ANSI standards for mechanical, thermal, and electrical performance.

3.2 Accessories & Protection

Standard ANSI pad-mount configuration:
• Oil temperature, oil level, winding temperature meters + drain valve
• HV fuses, load switches, 4-position selector switches
• Side-mounted instrument panel for monitoring and protection
• External grounding and shielding
• Lightning protection (rated arrester placement)

04 Packing and transportation