ABB PVS800-57-0100kW-A, Руководство по оборудованию, Страница: 76 / 180

74 Planning the electrical installation

Requirements for the transformer
•
suitable for the network and inverter AC voltage, current and power
•
suitable for use with IGBT inverters
•
degree of protection, temperature limits and lifetime are appropriate for the
environment
•
equipped with a static grounded screen between the high and low voltage windings
•
voltage withstand level of the low voltage winding is at least 1.6 kV against ground. A
typical voltage waveform against ground is shown below.
•
voltage rise time withstand level (d u /d t ) of the low voltage winding is at least 1000 V
per microsecond against ground.
•
recommended rated short-circuit impedance (X
k
) for each inverter is approximately
6% (±1%)
•
withstands low-voltage side current DC components of at least 0.5% of the nominal
rated current preferably without using an air gap
•
withstands the 3% total harmonic distortion generated by the inverter. However, we
recommend dimensioning the transformer for at least 5% total harmonic distortion to
withstand possible outside interference from the network.
ABB recommends that the transformer is equipped with an off-load tap changer for voltage
regulation on the high-voltage side of the winding with two 2.5% step points to the plus and
minus directions.
The inverter does not require any specific transformer notation. ABB recommends using
traditional notations, such as Dy11d0, Dy11y11, etc.
Do not ground the neutral (star) point of the transformer or connect it to the neutral points
of other windings.
t (ms)
U
AC-grid
(V)