4.4. MPPT grounding, detection of PV array insulation faults & Earth fault alarm
notification
The RS will test for sufficient resistive isolation between PV+ and GND, and PV- and GND.
In the event of a resistance below the threshold (indicating an earth fault), the unit will stop charging and display the error.
If an audible alarm and/or email notification of this fault is required, then you must also connect a GX device (such as the Cerbo
GX). Email notifications require an internet connection to the GX device and a VRM account to be configured.
The positive and negative conductors of the PV array must be isolated from ground.
Ground the frame of the PV array to local requirements. The ground lug on the chassis should be connected to the common
earth.
The conductor from the ground lug on the chassis of the unit to earth should have at least the cross-section of the conductors
used for the PV array.
When a PV resistance isolation fault is indicated, do not touch any metal parts and immediately contact a suitably qualified
technician to inspect the system for faults.
The battery terminals are galvanically isolated from the PV array. This ensures that PV array voltages cannot leak to the battery
side of the system in a fault condition.
4.5. Cable connection sequence
First:
Confirm correct battery polarity, connect the battery.
Second:
if required, connect the remote on-off, and programmable relay, and communications cables
Third
: Confirm correct PV polarity, and then connect the solar array (if incorrectly connected with reverse polarity, the PV voltage
will drop, the controller will heat up but will not charge the the battery).
4.6. Battery Connection procedure
Proceed as follows to connect the battery cables:
Use a torque wrench with insulated box spanner in order to avoid shorting the battery. Avoid shorting the
battery cables.
Specific care and attention must be taken when making the battery connections. Correct polarity must be
confirmed with a multimeter before connection. Connecting a battery with incorrect polarity will destroy the
device and is not covered by warranty.
• Undo the two screws at the bottom of the enclosure and remove the service panel.
• Connect the battery cables. First the - cable then the +. Be aware that there may be a spark when making the battery
connections.
• Tighten the nuts to the prescribed torques for minimal contact resistance.
Multi RS Solar
Page 10
Installation
