Services Provided

For all your Transformer and Mini- Sub requirements.

Cawse and Malcolm,
established 1893,

  • Supply & deliver reconditioned and refurbished transformers.
  • Collect, repair and deliver any type of transformer used in the Industrial sector.
  • Hiring out of transformers.
  • Supply & deliver new transformers
  • Recondition & refurbish mini-sub stations
  • Rewinding & testing of transformer cores
  • On site maintenance and oil purification
  • All testing conducted in terms of SABS specifications
  • Consultation for power and reticulation requirements

The Process

Manufacturing Transformers

Cores
The magnetic core is built from high quality CRGO lamination coated with oil and heat resistant insulation. Laminations are free from burrs, generally mitred cut and annealed in continuous annealing furnace for uniform heat treatment to minimize the stresses developed during slitting, cutting and punching.

Fully mitred designs are used to ensure low losses/low magnetizing current and low noise levels. Cores are adequately clamped by steel channels to keep it firm and erect.
Windings

 

Transformer Windings are designed to meet three fundamental requirements, such as mechanical, thermal and electrical. They are cylindrical in shape and are assembled concentrically.

According to Current and Voltage requirements. They can be of: (a) Spiral Type (b) Crossover Type (c) Helical Type (d) Continuous Disc Type. The coils are made from paper covered or synthetic enamelled copper or aluminium conductors of EC grade. Sufficient cooling ducts are provided to reduce the temperature rise of windings, oil and hot spot. All coils are pre-shrunk as per the seasoning cycle to withstand mechanical forces developed during short time overloads and short circuit conditions.
Tappings
Generally (+/-)2.5% to (+/-)5% tappings are provided on HV windings. Tapping adjustments may be made by an off-circuit tap switch operated by a handle on the outside of the tank (when the transformer is de-energised) with provision for padlocking on any particular tapping or by an on-load tap changer which can be supplied for hand operation, local, and remote electrical operation, or for fully automatic control.
Testing
All transformers are tested for all routine tests and heat run test as per IS:2026 at our works with modern, sophisticated, regularly calibrated meters through a centralized control panel.
Tests Conducted Are
1. Measurement of H.V. & L.V. winding resistance.
2. Measurement of voltage ratio and check-up of voltage vector relationship and polarity.
3. Measurement of impedance voltage / short circuit impedance (principal tapping) load loss.
4. Measurement of no load loss and current.
5. Measurement of insulation resistance.
6. Induced over voltage withstand test.
7. High voltage test on HV & LV windings.
8. Dielectric strength of transformer oil as per ISS:335.
Painting

The entire procedure of painting is done in two stages:

Cleaning of tanks
The cleaning of tank is done normally by chipping/grinding.
The outside surface of the tank is short blasted to achieve a very fine and smooth finish
Painting of tanks
After cleaning the tanks, a coat of hot oil resistance paint is applied on the internal surface of the tank.
The outside surface is painted with a coat of Red Oxide primer and subsequently with one coat of enamel paint as per customer's requirement.

Finishing
· Fittings and accessories as per customer's specification and drawing are checked.
· Air Pressure test is subjected to avoid any leakage and seepage on all transformer.
· Transformers are filled with oil up to the minimum level marking, wherever necessary.
· Loose accessories like, earthing terminals, bi-metallic connectors, dial type thermometers are also checked for proper fittings.