SMA SI 3.0-11 Installation - Manual (Page 17)

SMA Solar Technology AG 5 Product Description
Installation Manual SI30M-44M-60H-80H-IA-en-30 17
5.3 Multifunction Relay
Using two multifunction relays, each Sunny Island can control various functions and can display operating states and
warning messages. In battery backup systems, master multifunction relays are set permanently to control the contactors
within the automatic transfer switch.
Possible function or
output
Explanation
Controlling generators The multifunction relay activates if a generator request is received from the Sunny Island
inverter's generator management. With the multifunction relay, you can control generators
equipped with electrical remote-start function or connect a signal generator for generators
with no autostart function (see Section 7.4.10 and 7.4.11).
Control of the tie switch
and of the contactors for
grounding
In battery backup systems, the multifunction relays control the contactors for grid coupling
and grounding.
Control of load-shedding
contactors
The multifunction relay is activated depending on the state of charge of the battery.
Depending on the configuration, you can install a one-level load shedding with one
multifunction relay or a two-level load shedding with two multifunction relays. You can also
adjust the thresholds for the state of charge of the battery depending on the time of day
(see Section 7.4.12).
Time control for external
processes
The multifunction relays can be time-controlled (see Section 7.4.13).
Display of operating
states and warning
messages
Each multifunction relay can display either one event or one warning message
(see Section 7.4.14).
Control of a battery-room
fan
The multifunction relay is activated when the charging current leads to the battery emitting
gasses. A connected battery room fan is switched on for at least one hour (see Section
7.4.15).
Control of an electrolyte
pump
Depending on the nominal energy throughput, the multifunction relay is activated at least
once a day (see Section 7.4.16).
Use of excess energy In off-grid systems during the constant voltage phase, a multifunction relay is activated and
thus controls additional loads that can put any excess energy to good use (see Section
7.4.17).