Cast resin isolation transformers can be used in installations which require a Fire rating class of F1.

The transformers are designed to operate under natural convection of air. They can also be manufactured with a cross flow fan for controlled by the temperature controller for forced cooling to allow operation under extreme Australian conditions.

General features:

Cast resin transformer range is commonly used for Photovoltaic grid systems, Railway and UPS isolation systems. The transformers are routine tested for partial discharge <10pC and can also be impulse tested up to 400kV

  1. This transformer is rated F1 fire behaviour class, it is fire retardant and pollution free and can be directly installed close to load.
  2. Maintenance free transformer and allows simple installation and low operating cost
  3. This transformer shows excellent resistance to moisture and operates normally in regions with relative humidity of 100%.
  4. This transformer design features compact size and weight, low loss and noise level, high mechanical strength, low partialdischarge (under 10pC).
  5. The optional temperature probe and control system offers reliable protection to ensure safe operation. The temperature control system can be monitored and controlled by connecting it to a computer through its RS 485 serial interface.
  6. The transformer conforms to AS 60076 and IEC 726
  7. This transformer can be overloaded to up to 40% above its nominal rating with the use of cross flow fans.

Applications include:

Design Details



We live in a world where energy prices are constantly going up every year. Tortech’s solid resin cast transformer series can be built with Amorphous core material. Amorphous cores have typically 50% less no-load losses in contrast to conventional cores (typically 0.6W/Kg). Amorphous cores also run at lower flux density which means that they offer very good performance in installations which are subject to the presence of harmonics. We can also offer the transformer in high-quality cold rolled domain oriented silicon steel which is constructed in steps to reduce the magnetising current. The core is fastened and clamped together to reduce the noise caused due to magneto-striction.

HV Winding

The high voltage winding is constructed by solid cast epoxy which is poured under vaccuum using moulds for different voltage levels. The windings are constructed in a disc formation which provides linear distribution of voltage under impulse conditions. The epoxy is also prepared with a flexible anhydride hardener and a silica mix based filler which is flame retardant and provides F1 fire class rating. The inside and outside of the winding is also constructed using a glass fiber grid which provides mechanical strength and improves the performance under short circuit conditions.

LV Winding

The low voltage winding is constructed by using thin sheets of aluminium or copper. Aluminium is the preferred conductor winding material as the coefficient of expansion of aluminium and epoxy resin are similar. This protects the epoxy from cracking during constant heating/cooling of the transformer. Cracks will lead to increased partial discharge levels which accelerate and deteriorate the insulation material leading of insulation failure. Furthermore, the epoxy can be mixed with an aluminium hydrate compound which gives off water as a by product instead of fumes which results in better operation in tunnel installations.

Earth Screen

Solid cast Tortech transformers can be supplied with an electro-static screen. The screen is positioned at a calculated distance from the LV winding. This results in the filtering of common mode noise and harmonics. The higher frequency harmonics are shorted out to earth. The connecting wires to the screens also have a minimum cross sectional area to ensure low impedance between the screen and the earth. The chassis earth is connected using a seperate cable to ensure that the EMC voltage developed across the frame circuit due to capacitive currents from the shield remains minimised.

Available Products

Rated Power (kVA)Input / Output Voltage (v)Frequency (hz)Insulation ClassEfficiency (Amorphous Core)Efficiency (CGRO Core)Dimensions (l x w x h)WeightData Sheet
10011kV / 415V50/60F / H / C98.998.4730mm x 500mm x 816mm600kgDownload
16011kV / 415V50/60F / H / C99.098.4950mm x 650mm x 1124mm850kgDownload
20011kV / 22kV / 415V50/60F / H / C99.198.6990mm x 650 x 1164mm950kgDownload
31511kV / 22kV / 415V50/60F / H / C99.298.81050mm x 750mm x 1320mm1250kgDownload
50011kV / 22kV / 415V50/60F / H / C99.398.81140mm x 800mm x 1430mm1850kgDownload
80011kV / 22kV / 415V50/60F / H / C99.398.81330mm x 800mm x 1540mm2200kgDownload
100011kV / 22kV / 33kV / 415V50/60F / H / C99.398.81400mm x 960mm x 1640mm2750kgDownload
160011kV / 22kV / 33kV / 415V50/60F / H / C99.398.81560mm x 960mm x 1840mm4000kgDownload
200011kV / 22kV / 33kV / 415V50/60F / H / C99.398.81680mm x 960mm x 1930mm4800kgDownload
250011kV / 22kV / 33kV / 415V50/60F / H / C99.498.81720mm x 1010mm x 1950mm5500kgDownload

To inquire further, please contact our engineering team at: [email protected] or (02) 9642 6003.