Available in one, two or three phase applications.

Shaft length is variable.

Connection diagrams can be applied in any variation to all types.

These tap changers can be used either in oil or in askarel.

Welding the shaft bushing is needed.

Multi stage tap-changers can be provided after request.

The axis length can be provided as preferred .

More characteristics .

The tap-changer consists of :

-a mechanical position indicator,

-mechanical end stops,

-a padlocking facility for mechanical locking of the shaft for the hand crank (optional)

-Steel parts: mild steel.

-Drive shafts: mild steel.

-Springs: steel.

-Aluminium Parts : GAlSi12Cu

ON REQUEST

- The aluminium parts can be protected by anodic oxidation.

- The mild steel parts can be supplied in stainless steel.

- The brass and copper parts can be tin, silver or cadmium plated.

-Sealing : high quality Silicon material O-ring seals.

 Protection against corrosion: All parts outside are noncorrosive (steel A2, aluminium).

1. MECHANICAL CONTROL

-Hand Drive .The hand drive is installed to the transformer tank. It is used for mechanical operation of Off-Circuit Tap-Changers for transformers.

How it is working.

One of two parallel insulating strips supports the fixed contacts parallel to the drive shaft, and the other supporting the moving contacts. The fixed strip is attached to the mounting components in which the moving strip slides-driven by a pinion. A notch is provided to mark each position with precision. For any operation, the notch first of all must be released by applying an axial pull on the control knob; once the knob is facing its new position, it drops automatically into the respective notch under the action of a spring. The process of this operation is marked on the control knob with the inscription: OPERATION OFF CIRCUIT ONLY.

The hand drive is free of maintenance during the normal life time of a transformer (³ 30 years). Mechanical life time is 10.000 operations minimum.

2. CONTACTS:

-Fixed contacts: Made from copper by different design Flags.

Copper Parts: E-Cu F25 DIN 40500

On request: The fixed contacts can be tin ,silver or cadmium plated.

-Moving contacts :

Made from brass.

Brass Parts : CuZN40Pb2 Ms 60 F34 DIN 17673

On request can be supplied tin-silver or cadmium plated. Also can be supplied in copper.

3. VOLTAGES:

Voltage class	Max permissible voltage	Industrial frequency 50 Hz	Impulse 1/50
kV	kV	kV	kV
10	12	28	75
20	24	50	125
30	36	70	170

On request tap-changers can be designed for higher voltages.

4.CURRENT : up to 800A (Please quote for higher current).

5. CONTACT TESTS: a)Temperature rise test at rating current :and short-circuit current test according to IEC 214 standards. Results obtained are successful. b) Short-circuit current resistance: Temperature Range The Off-Circuit Tap-Changers can be used for an oil temperature range of -25 ° to +105 ° centigrade, i.e. -13° F to +221° F. For other temperature ranges please request.

On tap changers, are carry out rated short duration power frequency voltage tests. The tap changers are subjected to the short -circuit tests in accordance with IEC publication 76. The contacts bear no sign of pitting. The insulation was not damaged. According to the IEC Publication 542 (1976), icnl. Amendment No.1 "Application Guide for On-Load tap-Changers" the Off-Circuit Tap-Changers can work continuously with 1.2 times the rated through-current. The Off-Circuit Tap-Changers can be used with every transformer which is operated to IEC Publication 354(1991) "Loading Guide for Oil Immersed Transformers" and according to VDE Standard 0536 "Capability of Oil Immersed Transformers" and the standard ASA C57.92 "Guide for Loading of Oil Immersed Distribution and Power Transformers" and BS 171/CP 10 (1959) "Guide to Loading of Transformers".

6. INSULATION RESISTANCE: The insulators used are paper and phenoplastic resin-based laminates, thermal glass NEMA XX - DIN 7735 - HP 2061.5 - BSS 2572 P2- -VSM S-PF-CP2

7. MODIFICATION: In case we need to modify some particulars, in order to improve the quality of our products our firm reserve an option to change without a previous warning. Substantial modifications will be surely communicated.