Apply voltage drop and current carrying capacity calculations to select appropriate cables for a stand-alone PV energy system
This question will use table 9 and also the voltage drop formula applied in last question
The solar array is 15 metres from the solar controller and the solar cable will be buried in conduit in the ground. The controller is a standard controller and the battery bank is 48 V. The array has a maximum short circuit current of 26 A. Using the formula and the cables available in table 9 above what is the minimum sized cable that could be installed between the array and controller to ensure the cable can carry the required current and have less than 3% voltage drop.
Understand the need for and recognize the different modes of grounding (earthing) on a system as well as component level
Describe the difference between functional earthing (grounding) and protective earthing (grounding) in a PV array system?
Demonstrate the calculation and measurement of voltage drop in a conductor
This question will use the following formula for determining voltage drop in DC systems:
Resistivity can vary depending on number of strands and type of cable. For this examination we assume copper is 0.0183.
The solar array is 20 metres from the battery bank interconnected by a cable with cross sectional area of 10 mm2 . The controller is a standard controller and the battery bank is 24V. The array has a maximum short circuit current of 13A . What is the voltage drop between the array and the battery bank to three decimal places?
Perform safe techniques for laying, securing and terminating cables
Cables terminated on the flooded lead acid battery banks should be?
Specify appropriate protection for all conductors in a circuit
A string cable requires overcurrent protection, what should be the maximum rating of the protective device if the short circuit current for the module in the string is 6.8 A and the reverse current is 14 A?
Label, install and terminate electrical wiring, verify proper connections, continuity, voltage and polarity relationships
A continuity and polarity test shall be performed on the DC system. What should NOT be done when performing this test?
Discuss current carrying capacity and the implications for proper cable selection
The cable from the solar array will be mounted directly on the wall and exposed to direct sunlight. The maximum current will be 18 A, using table 9 what is the minimum size cable that selected to ensure it meets the current carrying capacity?