HET 500kVA/25kV,12.5kV,3kV Exciter Transformer

Mode: HET 500kVA/25kV,12.5kV,3kV
Rated capacitance: 500kVA
Single phase
Rated frequency: 50Hz
Rated input voltage:3kV
Rated input current:105.3A
Rated output voltage: Tap I:3kV ;Tap II:12.5kV Tap III :25kV
Rated output current:Tap I:166.7A;Tap II:40A ;Tap III:20A
Impedance voltage: < 5%
Cooling methods: ONAN
Insulation level: 1.1time rated voltage 1min
Insulation method: 25# Transformer oil
Using manual tap-changer convert voltage
Partial discharge :less than 5pC at rated voltage

Exciter transformer protection: equip piezoresistor for each HV output, exciter transformer’s input and output terminal connects with the ground via zinc oxide arrester, this methods can protect the operator and the equipment itself when test object breakdown. Structure: steel housing, HV bushing equips on the oil tank, equips wheels, movable, oil tank is shell-type, lead out the Low voltage with porcelain bushing. Each terminal is lead out by relative voltag grade bushing. HV bushing lead wire go through isovolumetric capacitance core, exterminal insulation is fiber glass bushing. Bushing has corona rings. Oil tank has oil conservator to make sure the capacitance core in the oil. HV bushing can guarantee 25kV corona free. Exciter transformer insulation characteristic: Exciter transformer insulation levelwill determin transformer’s safety work and insulation ageing speed. To guarantee no flashover- which coming from external, electric potential raise and cause damage to the main insulation and minor insulation. We will also set insulation layer between HV windings and turn-to-turn. Winding is cylinder type. Capacitance is determin by the winding’s area. When design, we’d try our best to make sure the top and bottom has same area, and compensate with electrostatic shield to improve the initial voltage distribution. Winding skeleton is made of compound insulation tube: can get down partial discharge and shielding the iron coil.

Principle Diagram: