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The UBB is a selector switch type of on-load tap-changer. It is designed for mounting inside of the transformer tank, but many of the features and benefits our customers appreciate from our UZ on-tank technology. This combination of the best qualities from both types of tap-changers makes the UBB model unique in its design and operation. Primarily designed for small and medium-sized transformers, the unit is compact and cost-effective compared to equivalent diverter switch types of tap-changers.

Product scope

  • Base technology: Conventional, resistance, in-tank, selector switch
  • Common applications: Network, special


  Tap-changer placed in the neutral point of the winding Other placements of the tap-changer
Highest voltage for equipment (Um) 76 kV 76 kV
Max lightning impulse (BIL) 350 kV 350 kV
Max current
1-phase (one tap-changer/phase)
500 A
500 A
500 A
500 A
Max step voltage 1500 V 1500 V


Why Hitachi Energy?

  • Compact size reduces overall space requirements in transformer to ensure cost effective solutions
  • Simplistic, reliable design philosophy ensures less complexity for reduced maintenance time and cost
  • Proven contact system has more than 40 years of service experience in more than 25,000 tap-changers

Get to know more

Document title ID
Technical guide 1ZSE 5492-106
Declaration of conformity 1ZSC000498-ABP
Ordering data form (.xlsm)
Please note that this is an interactive form, which can be filled in, saved and sent to us by e-mail.
Ordering data form explanations 1ZSC000498-AAR
User's manual 1ZSE 5492-156
Installation and commissioning guide 1ZSE 5492-118
Maintenance guide 1ZSE 5492-127
Repair guide 1ZSE 5492-130
Spare parts list 1ZSC000562-ACY
Accessories and protection devices 1ZSC000562-AAD
Oil filter unit, type HPS 27/27, 54 1ZSC000562-AAF
Oil filter unit, type OLU 1ZSC000562-AAR

Type designation Drawing number
UBBLT 5492 0088-1
UBBRT, UBBDT 5492 0088-2
UBBLN 5492 0088-3
UBBRN, UBBDN 5492 0088-4

The drawing shows Drawing number
Mounting on active part 5492 0088-8
Lifting tool for active part mounting 5492 0088-7
External drive shaft system 5492 0088-9
Bevel gear 5492 0083-1
Top section accessories 5492 0088-17
Connection of oil filter unit to top section 5492 0088-15
Recommended flange on transformer cover 5492 0088-11
Ball valve 1ZSC000772
Pressure relay 5492 0083-2
Oil flow relay 1ZSC003527-ABB
Pressure relief device - flow diameter 50 mm, standard - Comem 1ZSC003721-AAW
Pressure relief device - flow diameter 50 mm, class C5-M - Comem 1ZSC003721-AAV
Temperature relay 1ZSC003716-AAM
Tie-in resistors for UBBRN, UBBDN (136 kohm) 5492 0050-27
Tie-in resistors for UBBRN, UBBDN (204-300 kohm) 5492 0050-28
Tie-in resistors for UBBRT, UBBDT (136-200 kohm) except for 7-13 pos. 5492 0050-19
Tie-in resistors for UBBRT, UBBDT for 7-13 pos. 5492 0050-34

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