Medium-Voltage Transformer; Requirements Of The Medium-Voltage Transformer - Bosch BPT-C 200 Betriebsanleitung

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Bosch Power Tec GmbH
4.4

Medium-voltage transformer

The central inverters are designed for direct grid connection to a medium-
voltage transformer. They are central inverters without integrated
transformers and thus without galvanic isolation between the solar
generator and the electricity grid. Galvanic isolation is provided exclusively
by the medium-voltage transformer.
 Option 1: Use a medium-voltage transformer
 Or option 2: Use a shared medium-voltage transformer with galvanically
isolated low-voltage coils.
Please note the following here:
For earthed solar generators: Only use option 2 (with the galvanically

isolated low-voltage coils).
For questions regarding transformer design: Contact the manufacturer

If you are using a transformer without isolated low-voltage coils, you can
connect a maximum of four central inverters.
Please note the following here:
Do not earth the solar generator

Transformer must be suitable for use on the central inverter.

If you earth the solar generator, each central inverter must have a separate
medium-voltage transformer or a separate low-voltage coil.
4.4.1

Requirements of the medium-voltage transformer

Suitable for operation with IGBT (Insulated Gate Bipolar Transistor) based

pulsed inverters. By using pulsed inverters, voltages to earth of up to
1500 V can occur.
DC
You can find information on the distortion factor (Total Harmonic

Distortion, THD) and the DC proportion in the AC in the technical
specifications.
Short-circuit voltage U

K
When creating the thermal design of the medium-voltage transformer,

consider the load curve and the ambient conditions of the installation
location.
Low-voltage side 200 kVA
(secondary side)
Interlinked voltage 300 V
(between the phases)
Rated power 200 kVA
Vector group Dyn5, Dyn11 or
Dd0
Short-circuit voltage 4–6%
Medium-voltage side (primary side)
In accordance with the specifications of the energy supplier
If you combine transformerless central inverters with another of the
manufacturer's inverters, you must use corresponding medium-voltage
transformers.
= 4–6%, based on the inverter
300 kVA
300 V
eff eff
300 kVA
Dyn5, Dyn11 or
Dd0
4–6%
BPT-C 200, 300, 350 | Operating manual
Installation location | 47
350 kVA
315 V
eff
350 kVA
Dyn5, Dyn11 or
Dd0
4–6%