MWA300 and MWA330A

3-phase ratio and winding resistance analyser

  •   Combines TTR and resistance testing in one box - faster, more efficient testing
  •   55% smaller, 40% lighter than individual instruments
  •   Only one set of leads required - lighter, smaller and less expensive
  •   One test form - easier, faster to complete
  •   Built-in demagnetisation

The Megger MWA300 and 330A Transformer Winding Analysers are here to offer you a faster, more efficient testing device through combining TTR and resistance testing in a single unit.

This advanced 3-phase transformer test system provides complete ratio, phase and winding resistance measurements with only one 3-phase lead-set connection. What’s more, it offers portability, a reduced set-up time and increased job safety.

Once connected, the MWA300 performs DC resistance measurements on all high- and low-side windings without reconnection. It has an 8-terminal/6-winding resistance measurement capability and doesn’t need any inter-connected boxes, allowing you to test all 6 windings without having to disconnect and reconnect leads.

The MWA300 series saves you even more time by using a single software platform, PowerDB, which means you only need one set-up and one easy-to-use test form.

The MWA300 series can be used effectively test power transformers, distribution transformers, CTs and VTs, and motors and generators.

The following tests are easily performed with a single instrument, the MWA300 series, and a single 3-phase lead set connection:

  •   3-phase turns ratio
  •   3-phase winding resistance
  •   OLTC continuity (make-before-break)
  •   3 phase core demagnetization
  •   Magnetic balance / flux distribution
  •   Excitation current
  •   Polarity and phase angle deviation
  •   Auto vector detection
  •   Heat-run test

The MWA330A comes equipped with a built-in computer that has a 305 mm (12 in) colour display and touch-screen interface. The computer is designed to control the unit and it can store up to 100, 000 data sets.

Product Documents
Quick start
Quick start guide - MWA300
Transformer Test Instrument Software Updates for TTR330A, MTO330A, MWA330A, DELTA4310A

The following components have been updated:

PowerDB ________________ V11.2.10 

MTOTestXP ______________ 2019.12.03.1

Delta Manual Control ______________   

Instrument Config ______ 1.0.20023.1919

Splash Screen __________ 1.0.21075.830

Factory Config _________ 1.0.21122.850

Megger Update Manager __ 1.0.21165.1032



- Megger recommends that you return your instrument annually for calibration verification.
- Any instrument returned for re-calibration will be updated with the latest firmware and software versions.
- Certified Factory Calibration is valid for one year.


Incorrect installation of updates or incomplete updates may cause the equipment to become unusable.

If damage occurs from improper updates, the customer may be responsible for repair costs.

Software updates for TTR330A, MTO330A, MWA330A and DELTA4310A

Download this zip file, extract, and run the executable.


256bit Hash:

763 MB | 02/08/2022
745.9 MB | 09/08/22
Update Instructions

Please download and read these instructions before performing the update.


623.9 KB | 09/08/22