SMA SI-TB-BOX-10 - Manual (Page 17)

SMA America, LLC 4 Product Description
Installation Manual SI_TDBOX-IA-eng-IUS122211 17
Symbols on the Smartformer
4.2 Autotransformer
The autotransformer enables the following functions in a Sunny Island:
• Integration of PV inverters with an AC output voltage of 240 V
• Supply of AC loads with 120 V or 240 V
The autotransformer converts the input voltage according to the load requirements, operating in the
step-up and step-down operating modes.
• Step-up:
The Sunny Island makes an AC input voltage of 120 V available. The autotransformer converts
this AC input voltage into an AC output voltage of 240 V. The loads use one AC output with
120 V or both AC outputs with 240 V. A different load on the two 120 V outputs is
compensated by the Smartformer through power transmission.
• Step-down:
The PV inverter makes an AC input voltage of 240 V available. The autotransformer converts
this AC input voltage into an AC output voltage 120 V. The Sunny Island uses this voltage to
load the battery.
Unlike in other transformers, the input circuit and the output circuit of the autotransformer are not
galvanically isolated.
Symbol Description Explanation
Spring clamp terminals Some of the terminals of the Smartformer are
executed as spring clamp terminals.
Always connect a conductor to a spring
clamp terminal as described in this document
(see Section 6.5 "Connecting Insulated
Conductors to Spring Clamp
Terminals", page 39).