33
4.8.5
Selecting PV string fuse(s)
A
= 2 String Fuse
Holders (black)
A
Figure 30: String fuse locations
4.8.5.1
PV string fuse information and calculating string fuse size
The PVI 3800TL, PVI 5200TL, PVI 6600TL, and PVI 7600TL inverters are shipped with 3 X 15 A
600Vdc Littlefuse KLKD 15 string fuses. The provided string fuses may or may not be appropriate
for your particular installation. Proper sizing of overcurrent protection is based on the maximum
short circuit current Isc (module) and calculated in accordance with NEC Article 690 requirements.
The maximum acceptable string fuse for the PVI Inverter is 20 A
(KLKD 20). Use of larger fuses will void the warranty.
The string fuse rating should never exceed the Maximum Series
Fuse Rating provided by the module manufacturer. This value is
typically listed on the module label.
WARNING!
AVERTISSEMENT!
NOTICE!
AVIS!
4.8.5.1.1 Calculating the minimum string fuse per NEC Article 690
The minimum string fuse size is calculated by multiplying the module Isc x 1.56.
Thus, if we are using modules that have an Isc = 6.25 A, we would calculate our minimum string
fuse size as follows:
String Fuse (minimum) = 6.25 A x 1.56 = 9.75 A
Reviewing our Littelfuse KLKD series fuses, we find that 10 A is the next available fuse size. Thus,
to satisfy the minimum string fuse requirements per NEC Article 690, we would remove the 15 A
fuses shipped with the inverter and replace them with 10 A fuses.
A partial listing of the Littelfuse KLKD Fuses is as shown.
Part Number
Amperage
KLK D 008. ............................ 8 A
KLK D 009. ............................ 9 A
KLK D 010. ............................ 10 A
KLK D 012. ............................ 12 A
KLK D 015. ............................ 15 A
KLK D 020. ............................ 20 A
