Medium Three Phase Oil Immersed Distribution Transformer

Product Overview

CNHK Medium Oil Immersed Transformers are used to step down three phase high voltage to low voltage for powerdistribution, mainly in metropolitan areas and for industrialapplications. The transformers in standard versions aredesigned for use in moderate climates and can be installed both outdoors and indoors.
Medium transformers are hermetically sealed (the tank is completely filled with oil) or equipped with oil conservator.Both types are equipped with flexible corrugated tank walls enabling sufficient cooling of the transformer.

They also compensate for the changes in the oil volume during operation. An advantage of the hermetically sealedtransformers is that the oil is never in contact with the atmosphere thus avoiding periodic oil analysis.

Type Designation

Constitution

Core

The cores of the transformers are made of grain-oriented magnetic, cold-rolled silicon steellaminations with low losses

Windings

The windings of the transformers are made of high grade electrolytic copper or aluminium. The High Voltage windingsare wound either with round, enamel insulated, or shaped, paper insulated wire. The Low Voltage windings are woundwith shaped, paper insulated wire or foil. The winding construction is characterised by high dielectric strength with high resistance,
To atmospheric surges and to the effects of short-circuits. Neutral points of the Low Voltage windings are brought to the tank cover.

Basic structure

-3 HV porcelain sleeves
-4 LV porcelain sleeves
-Exhaust valve (optional)
-Filling port
-Lifting ring
-Welded square bracket at tank bottom
-2 grounded sockets
-Nameplate
(Rated power >1000 kVA):
Additionally, for transformers with conservator(Optional)
– Max thermometer

Magnetic oil-level indicator
Oil filling port on the conservator
Buchholz relay
Dehydrating breather
– Conservator

Container color:

RAL 7033.or customized

Standards and specifications:

IEC 60076

Power range:

315-400-500-630-800-1000-1250-1600-2000-2500KVA.

Description:

Oil-immersed sealed transformer or with conservator

Cooling type: ONAN

Outdoor high pole installation.

Rated Frequency:

50 Hz (standard)/60 Hz(optional)

Rated voltage:

HV side: 11000, 22000, 33000V and etc.

LV side:400-410-415-420V

Off-load Tap Changer (NLTC):

3 taps or 5 taps on HV winding:5%, +2.5% when Transformer is deactivated

On-load Tap Changer(OLTC):

7 taps or 9 taps on HV winding : +3*2.5%, 14*2.5% ( optional)

Vector Group:

Yy, Yz, Dy, Dd, Yd

Options And Accessories

– Plug-in bushings
– Dial type thermometer with two contacts
– DGPT2 control device
– Pressure relief valve with or without contacts
-Tap changer with more than five positions
– Cable boxes
-Spark gap meter
– Air insulated housings
– Galvanized tank
– Additional thermometer pocket
– Dual voltage transformer

Specification Table

Typical Data for Medium Three phase Oil Immersed Distribution Transformer HKS11-315kVA to 2500kVA, Up to 38.5kV, NLTC

* NLTC: No-load Tap Changer
* Provide +5% or +2×2.5% off-load tap changer
* Tank Type: H: Hermetically sealed with corrugated tank
C: Corrugated tank with conservator

Typical Data for Higher Effiency Medium Oil Immersed Transformer HKS18, HKS20, HKS22 Series for Optional, Up to 38.5kV, NLTC

* NLTC: No-load Tap Changer