System Design; Design Considerations; Fuse Rating - SMA STRING-MONITOR SSM-U-2410 Technical Information

SMA Solar Technology AG

3 System Design

3.1

Design Considerations

When designing an SMA String-Monitor, take the following aspects into account:
• Maximum current values

• Fuse rating

• Specifics for installation altitudes over 2,000 m
• Ambient temperatures over 50°C
3.2 Maximum Current Values
The following current values must not be exceeded:
• Rated current (I
DCmax
• Rated current (I
DCmax
• Rated current per measurement input: 17.5 A
The following applies:
I = I / number of string inputs ≤ 17.5 A
String_max DC_max
The rated current applies for a maximum irradiation of 1,200 W/m
radiation). In case the irradiation is higher, the rated current must be adapted linearly downwards.
3.3 Fuse Rating
If you are using the inline fuse connectors offered by SMA Solar Technology AG, you can find information on the fuse
rating in the Technical Information "IFCON Inline Fuse Connector Set16".
If you are using other fuses, you can find information on the fuse rating in the datasheet of the fuse manufacturer.
When selecting the fuse nominal values (I
short-circuit current of the connected PV array under standard test conditions (I
The following applies:
I ≤ I x reduction factor or I
SC_STC nom
3.4 Specifics for installation altitudes over 2,000 m
3.4.1 Reduction of Maximum Fuse Current
When installing at altitudes over 2,000 m, an additional reduction factor for the fuse rating needs to be taken into
account (when using the inline fuse connectors offered by SMA Solar Technology AG, see the Technical Information
"IFCON Inline Fuse Connector Set16"; when using other fuses, see the datasheet of the fuse manufacturer).
3.4.2 Reduction of the Electrical Parameters of the DC Load-Break Switch
The current is not being reduced.
The rated voltage is reduced as follows:
• For installation altitudes of 2,001 m to 3,000 m = reduction by 1.0% per 100 m
• For installation altitudes of 3,001 m to 4,000 m = reduction by 1.2% per 100 m
3.4.3 UV Radiation
UV radiation increases by approximately 1.5% for every 100 m of altitude. For example, the UV radiation at an
altitude of 4,000 m is approximately 30% stronger than at an altitude of 2,000 m.
UV radiation has damaging effects on plastics.
Technical Information
) up to 50°C: 315 A
DC
) over 50°C: reduction by 2.5% per K
), a reduction factor according to the manufacturer specifications for the
nom
≥ I / reduction factor
nenn SC_STC
DC
2
(hourly average value of the horizontal global
3 System Design
) needs to be applied.
SC_STC
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