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Isolation Transformer

by AltraVolt Power

Galvanic isolation and common‑mode noise rejection for medical equipment, data centers, test labs, and sensitive electronics — designed to IS 2026 / IS 1180 norms.

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AltraVolt Isolation Transformer
Isolation

Overview

The AltraVolt Isolation Transformer provides complete galvanic isolation between the input (primary) and output (secondary) windings, with no direct electrical connection. This protects sensitive equipment from common‑mode noise, ground loops, and earth leakage currents, while enhancing operator safety by removing a direct shock path back to the source. Available in single‑phase and three‑phase configurations from 0.5 kVA to 2500+ kVA, with ratios from 1:1 (standard isolation) to step‑up/step‑down for voltage conversion.

Built to Indian Standards (IS 2026 series, IS 1180) and optionally to IEC 61558 / IEC 60601‑1 for medical/export applications, our transformers use CRGO silicon steel cores, high‑grade copper windings, and electrostatic shielding to achieve excellent noise attenuation and dielectric strength (typically 2–4 kV between windings).

How It Works

⚡ Galvanic Isolation

The primary and secondary windings are physically separated by insulation and are only magnetically coupled via the iron core. There is no conductive path between input and output, so any common‑mode voltage (noise that appears equally on both supply lines relative to earth) is blocked. This eliminates ground loops and prevents leakage currents from flowing through connected equipment.

🛡️ Electrostatic Shielding

An electrostatic shield (a grounded copper foil between windings) attenuates high‑frequency common‑mode and differential‑mode noise, providing excellent EMI/RFI rejection. This is critical for medical devices, lab instruments, and data centres where clean power is essential for accurate measurements and reliable operation.

Key Features

🔌

Galvanic Isolation

Complete electrical separation of input & output for safety and noise rejection.

🛡️

Noise Attenuation

Electrostatic shielding reduces common‑mode & differential‑mode EMI.

⚡

High Efficiency

≥97–99% efficiency, minimising energy losses.

📐

Flexible Ratios

1:1, step‑up, or step‑down configurations available.

🌡️

Wide Capacity Range

From 0.5 kVA to 2500+ kVA, single‑phase or three‑phase.

✅

Standards Compliant

Designed and tested per IS 2026, IS 1180, IEC 61558, IEC 60601‑1 (medical).

Benefits

Ideal Applications

🏥 Medical & Healthcare

  • MRI, CT, X‑ray, ultrasound machines
  • Patient monitoring systems
  • Operating theatre equipment
  • Dental and diagnostic devices

💻 Data Centres & Telecom

  • Server racks and network infrastructure
  • Telecom base stations and exchange equipment
  • UPS input isolation

🔬 Test Labs & R&D

  • Calibration and measurement instruments
  • Electronics testing and prototyping
  • University and research labs

🏭 Industrial Automation

  • PLC systems and control panels
  • Robotics and CNC controllers
  • Sensitive process instrumentation

Technical Specifications

Capacity Range

0.5 kVA to 2500+ kVA

Configuration

Single‑phase & three‑phase; 1:1, step‑up, or step‑down ratios

Isolation

Galvanic separation of primary & secondary windings (no direct electrical path)

Dielectric Withstand

Typically 2 kV – 4 kV+ between windings (per IS 2026 Part 3)

Voltage Regulation

± 1–2% depending on design (static, no moving parts)

Cooling

Dry‑type (air/cast‑resin) or oil‑immersed depending on kVA & site needs

Noise Rejection

Common‑mode & differential‑mode EMI attenuation via electrostatic shielding

Efficiency

> 97–99%

Winding Material

Copper (CRGO core lamination for low losses)

Insulation Class

Class H / F insulation common in dry‑type units

Reference Standards

IS 2026 (Parts 1,2,3,5,8), IS 1180, IS 335 (oil), IEC 61558, IEC 60601‑1 (medical)

Isolation Transformer vs. Servo Stabilizer

While both are power‑conditioning devices, they serve different primary purposes:

Feature Isolation Transformer Servo Voltage Stabilizer
Primary Function Galvanic isolation & noise rejection Voltage regulation (±1%)
Connection No direct electrical path between input and output Direct path (autotransformer) with motor‑driven correction
Noise Filtering Excellent common‑mode & differential‑mode attenuation Limited (may include filters, but not the primary design)
Safety Eliminates shock path, protects personnel Provides over‑voltage/under‑voltage cut‑off but does not isolate
Voltage Correction None (fixed ratio; output follows input ratio) Active correction to maintain output at set voltage
Typical Applications Medical, labs, data centres, sensitive electronics Industrial machinery, HVAC, commercial buildings

Note: In many critical installations, both devices are used together — a servo stabilizer corrects voltage, and an isolation transformer provides safety and noise isolation.

Indian Standards (BIS) for Transformers & Isolation Units

Isolation transformers are governed by the same core BIS transformer standards used across the Indian power equipment industry. Below are the key parts and their relevance.

IS 2026 (Part 1):2011 — Power Transformers, General

The umbrella standard for power transformers in India. Defines terminology, rated voltage and power conventions, tapping ranges, vector group/winding connection notation, and general design obligations that apply equally to step‑up/step‑down transformers and 1:1 isolation transformers.

IS 2026 (Part 2):2010 — Temperature Rise

Sets permissible winding and oil/air temperature rise under rated continuous load, with normal ambient assumptions of −25°C to +40°C for oil‑immersed designs. References transient loading calculation methods (IS 6600) relevant for intermittent high‑inrush loads like lab equipment.

IS 2026 (Part 3):2009 — Insulation Levels, Dielectric Tests & Clearances in Air

This part is most directly relevant to "isolation" performance — it sets the required dielectric (high‑voltage withstand) test levels between windings and to earth, and the minimum physical clearances in air between live parts of different potential. The typical "4 kV dielectric" or "2.5 kV withstand" figures quoted for isolation transformers are tested against this part.

IS 2026 (Part 5):2011 — Ability to Withstand Short Circuit

Specifies how the transformer must withstand the thermal and dynamic effects of external short circuits — including line‑to‑line, double‑earth, and line‑to‑earth faults — without sustaining damage, based on the system's short‑circuit apparent power.

IS 2026 (Part 8):2009 — Application Guide

Practical guidance on selecting and applying power transformers correctly — loading practices, parallel operation, and de‑rating considerations — often referenced when isolation transformers are specified for non‑standard duty cycles.

IS 1180 — Outdoor Type Distribution Transformers

Governs oil‑immersed distribution transformers up to 2500 kVA, 33kV class — relevant where a larger isolation transformer is built on a standard distribution‑transformer chassis for outdoor/industrial installation.

IS 335 — Insulating Oil

Applies to oil‑immersed isolation transformers, governing dielectric strength, moisture content, flash point, and viscosity of the mineral oil used for cooling and insulation.

Dry‑Type Construction — A Note on IS 11171

Many isolation transformers (especially smaller medical/lab/electronics‑grade units) are dry‑type (cast‑resin or VPI‑varnished, air‑cooled, no oil). These were historically built with reference to IS 11171:1985, "Dry‑Type Power Transformers" — however, this standard has since been declared withdrawn by BIS. Current dry‑type designs typically reference IS 2026's relevant parts directly (which now incorporate dry‑type clauses) and/or the IEC 60076 series internationally. Always verify the live, current edition before printing a standard number on a datasheet.

CE Marking, UL & Medical‑Grade Compliance

For medical and export applications, isolation transformers are often additionally tested against IEC 61558 (safety of isolating transformers for general use) or IEC 60601‑1 related clauses where feeding patient‑connected equipment, alongside CE marking for the European market and UL recognition/listing for North America.

Practical tip when quoting standards on a datasheet: Cite the BIS part number together with the year of the edition you're actually testing/manufacturing against (e.g. "IS 2026 (Part 3):2009") rather than just "IS 2026," since different parts have different revision years and some older referenced standards (like IS 11171) have been withdrawn.

Installation & Maintenance

🛠️ Installation Guidelines

  • Place the transformer in a well‑ventilated area, away from direct sunlight and moisture.
  • Ensure input and output wiring are correctly sized for the current rating.
  • Connect the earth ground properly — the transformer frame and electrostatic shield must be earthed.
  • For oil‑filled units, ensure adequate clearance for oil expansion and periodic oil sampling.
  • Allow at least 30 cm clearance on all sides for airflow (dry‑type) or for maintenance access (oil‑type).

🔧 Routine Maintenance

  • Visually inspect for dust accumulation every 6 months; clean with a soft brush or vacuum.
  • Check all electrical connections for tightness.
  • For oil‑filled units, periodically test the oil's dielectric strength and moisture content per IS 335.
  • Monitor operating temperature and ensure cooling systems (fans, radiators) are functioning.
  • For dry‑type, inspect insulation surfaces for cracks or contamination.

Frequently Asked Questions

What is the difference between an isolation transformer and a servo stabilizer?

An isolation transformer provides galvanic isolation and noise filtering but does not regulate voltage. A servo stabilizer actively regulates voltage (keeps output at a set level) but does not provide isolation. They are often used together for complete power conditioning.

Do I need an isolation transformer for my home office?

If you have sensitive audio/video equipment or a high‑end PC, an isolation transformer can help eliminate ground loops and noise. However, most modern electronics have internal filters. For medical or lab use, isolation is often mandatory.

Can I use a 1:1 isolation transformer for voltage conversion?

A 1:1 transformer only provides isolation; the output voltage equals the input (minus small losses). If you need to convert voltage (e.g., 240V to 110V), you need a step‑down or step‑up transformer (which also provides isolation, but with a different turns ratio).

What is the difference between dry‑type and oil‑immersed isolation transformers?

Dry‑type transformers use air or cast‑resin for insulation and cooling; they are suitable for indoor applications where oil is undesirable (e.g., hospitals, data centres). Oil‑immersed transformers use mineral oil for better cooling and higher capacity; they are more commonly used outdoors or in heavy industrial settings.

How do I choose the right kVA rating?

Calculate the total load (in VA) of the equipment you intend to protect. Add a safety margin (typically 20–30%) to account for future expansion and inrush currents. Our team can assist you with sizing for your specific application.

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