Okay, Howard, this is definitely an interesting situation. Let's break this down and explore the best options, focusing on safety, code compliance, and cost-effectiveness.

Understanding the Problem Single-Phase Service

You have a single-phase 200A service at (presumably) 240V (or 208V depending on your locale).

Three-Phase Load

The trailer needs 480V 3-phase at 30A. That's a significant load.

No Three-Phase Availability

Bringing in three-phase service from the utility is likely very expensive.

The Core Issues & Potential Solutions

Your initial instinct is correct. You will need a step-up transformer AND a phase converter. Here's the breakdown:1. Step-Up Transformer

This will take your existing single-phase voltage (e.g., 240V) and step it up to 480V.2.

Phase Converter (Crucial)

This device takes the single-phase 480V from the transformer and synthesizes a 3-phase output, allowing you to power the trailer.

Detailed Analysis and Recommendations Sizing Considerations

This is critical. You MUST calculate the VA (Volt-Amps) of the 3-phase load to properly size the transformer and phase converter. Trailer Load: 480V x 30A x √3 (square root of 3) = approximately 24,942 VA. Accounting for Safety Margin: It's wise to add a safety margin (e.g., 25%). 24,942 VA x 1.25 = 31,178 VA. Therefore, you'll likely want to use a

30-35 KVA transformer and a phase converter rated for at least that amount of power. Transformer Selection

You'll need a single-phase step-up transformer. It should have a primary voltage matching your existing service (e.g., 240V) and a secondary voltage of 480V. Look for a KVA rating of at least 35 KVA.

Example

A good starting point for searching would be "35 KVA single phase 240V to 480V step up transformer." Brands like Acme, Hammond, and Jefferson are common.

Phase Converter Selection



Rotary Phase Converter (RPC)

These are generally preferred for motor loads like refrigeration compressors because they can handle inrush currents and provide a more stable voltage. However, they require more maintenance.

Static Phase Converter

These are less expensive but generally not recommended for motor loads. They may have issues with starting and running the refrigeration equipment.

Digital/Solid-State Phase Converter

These are becoming more common and offer good performance with electronic control and often better voltage balance. They can be more expensive than rotary converters.

Recommended Phase Converter Brands/Models (as a starting point for your research)



Phase-A-Matic

Rotary and Digital models available. They have good reputations. Check their website for models that can handle the KVA you need.

American Rotary

Well-known for rotary converters.

North American Phase Converters

Offers both static and rotary models.

WEG

Makes solid-state phase converters (check ratings).

IMPORTANT: Derating and Over-Sizing

It's critical to consult the manufacturer's specifications for both the transformer and the phase converter. They may require derating based on ambient temperature, altitude, and other factors. Over-sizing the phase converter, particularly, can be beneficial to handle inrush currents from the refrigeration compressor.

Wiring and Protection



Primary Side (240V)

You'll need appropriately sized overcurrent protection (fuses or circuit breakers) for the transformer primary. Calculate this based on the transformer KVA and the primary voltage.

Secondary Side (480V)

You'll need overcurrent protection at the output of the phase converter before it goes to the trailer.

Grounding

Proper grounding is essential for safety. Follow all applicable electrical codes.

Permitting and Inspection

This is a MUST. Any electrical work of this scale will require permits and inspection by your local electrical inspector. Discuss your plan with them before starting any work. They may have specific requirements or preferences.

Step-by-Step Implementation Plan1. Verify Trailer Requirements

Double-check the trailer's exact voltage, phase, and amperage requirements. Also, find out if there are any special starting current requirements for the refrigeration compressor. Get the manufacturer's data sheet for the trailer.2.

Electrical Load Calculation

Perform a detailed electrical load calculation for the entire service, including the existing loads and the new trailer load. This will help determine if the 200A service is sufficient.3.

Consult with Suppliers

Contact suppliers of transformers and phase converters. Explain your situation and ask for recommendations based on the trailer's specifications. Get detailed specifications and pricing.4.

Consult with the Electrical Inspector

Discuss your proposed plan with the local electrical inspector. They can provide valuable guidance and ensure code compliance.5.

Select Equipment

Choose the appropriate transformer and phase converter based on your calculations, supplier recommendations, and the inspector's approval.6.

Installation

Have a qualified electrician install the equipment, following all applicable electrical codes and manufacturer's instructions.7.

Inspection

Schedule an electrical inspection after the installation is complete.

Important Considerations & Warnings



200A Service Capacity

A 30A 480V 3-phase load is significant. You must ensure that the existing 200A service has sufficient capacity to handle the new load. A load calculation is non-negotiable. You may need to upgrade the service.

Voltage Drop

Long wire runs can cause voltage drop, especially with motor loads. Use appropriately sized conductors to minimize voltage drop.

Safety

Working with 480V can be dangerous. Ensure that all work is performed by a qualified electrician and that all safety precautions are taken.

Code Compliance

All work must comply with the National Electrical Code (NEC) and local electrical codes.

Customer Expectations

Make sure the customer understands the limitations of using a phase converter. While it's a viable solution, it's not the same as having true three-phase power from the utility. Explain potential issues with voltage balance and motor starting.

Alternative: Generator

Depending on the usage pattern of the trailer, it might be more cost-effective to use a three-phase generator. While there are upfront costs for the generator, the efficiency and maintenance of the phase converter might outweigh it. Consider this option for the customer.

Example - Possible Parts (Note: You MUST verify these with the specific application)



Transformer

Acme T-1-53772-3S (37.5 KVA, 240V Primary, 480V Secondary). Verify the primary voltage matches your situation.



Phase Converter

Phase-A-Matic Rotary Phase Converter (Consult their catalog based on KVA).

Disclaimer: I am an AI chatbot and cannot provide electrical engineering advice. This information is for general guidance only. Consult with qualified electrical professionals for all electrical work.*This is a complex project. Take your time, do your research, and prioritize safety and code compliance. Good luck, Howard! Flag for review