Overcurrent Protection Devices - Eltek Valere Theia He-t User Manual

3.3.1. Disconnection Devices
Disconnection devices, switches or circuit breakers, enable a shut-off from the power
source during operation. They protect the current-carrying conductors and other system
components from power surges and system malfunctions, and help to shut down the inverter
safely for maintenance and repairs.
• Both AC circuit breaker(s) and DC switch(es) are recommended to facilitate maintenance
work and repairs of the inverter.
• The disconnect devices must conform to the local and national electrical regulations, and
have an interrupt rating sufficient for the voltage and current available in the circuit.
• Each disconnection device must be readily accessible and operable without exposing the
operator to live parts. All devices must be permanently marked for their purpose.
• Good practice is to switch OFF the AC circuit breaker(s) before the DC switch(es) to reduce
wear of the contacts.

3.3.2. Overcurrent Protection Devices

Overcurrent protection devices, fuses or circuit breakers, prevent the circuit conductors
from overheating as a result of overload, short circuit or ground fault.
• An overcurrent protection device is required on every live wire.
• If a fuse blows or a circuit breaker trips the cause should always be determined before
replacing or resetting them. Contact the system installer, for assistance.
• It is recommended to install an RCD (Residual Current Device) of type B on the supply
side of the inverter, to be able to detect leakage current and interrupt fault paths. Devices
must comply with the relevant local and national electrical regulations!
DC Fuses
• DC fuses protect the conductors from back-feed currents from parallel strings. They are
located in the lower compartment of the stringbox, equipped with finger-safe fuse holders to
disconnect each fuse independently (See
• The rating of the DC fuses should be as per the recommendations of the PV module
manufacturer and the local and national electrical requirements.
• DC fuses are not required for the DC circuits where the short circuit currents (I
PV modules cannot exceed the rated current carrying capacity of the PV circuit conductors
or the maximum overcurrent device size specified on the PV module product label.
• The size of the DC fuses required must be specified at the time of order.
Table 3.3.1: DC current characteristics and fuse rating
Inverter Type
THEIA 2.0 HE-t
THEIA 2.9 HE-t
THEIA 3.8 HE-t
THEIA 4.4 HE-t
User Manual THEIA HE-t String Inverters
4.3.2. Connection
Max DC Current Min Fuse Rating
9.5A
13.5A
18.0A
21.0A
357115.013
Area).
Max Fuse Rating
12 A
17 A
23 A
27 A
,
Issue 1.0, 2011 April
) from all
SC
20 A
30 A
35 A
40 A
15