MWA300 and MWA330A

MWA300 and MWA330A

Three-phase ratio and winding resistance analysers

  •   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 MWA330A three-phase ratio and winding resistance analysers are advanced transformer test systems that provide complete ratio, phase, and winding resistance measurements with only one three-phase lead set connection. What’s more, they offer portability, a reduced set-up time, and increased job safety.

Once connected, the MWA300 and MWA330A perform DC resistance measurements on all high- and low-side windings without reconnection. It has an eight-terminal/six-winding resistance measurement capability and doesn’t need any interconnected boxes, allowing you to test all phase windings without having to disconnect and reconnect leads.

The MWA300 and MWA330A save you even more time by using a single software platform: PowerDB. This means you only need one setup and one easy-to-use test form.

The MWA300 and MWA330A can be used to effectively test power transformers, distribution transformers, CTs and VTs, and motors and generators. The following tests/functions are easily performed with a single instrument and one three-phase lead set connection:

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

The MWA300 is externally controlled by PowerDB software running on an external PC. The MWA330A, on the other hand, comes equipped with its own built-in computer that can be operated via a 305 mm (12 in) colour touch screen display and 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 | 06/05/23
Update Instructions

Please download and read these instructions before performing the update.


623.9 KB | 06/05/23