Section 2 Understanding Rebus; Introduction; Power Distribution; Device Communications - Generac Power Systems PWRcell Reference Manual

Understanding REbus
Section 2

Introduction

Understanding REbus is crucial for the safety and
performance of all PWRcell equipment.
REbus stands for Renewable Energy bus. It is the
trademarked name for Generac's patented DC bus.
REbus requires a three-wire connection, Positive,
Negative, and Ground, between PWRcell devices and
the inverter.
Two main functions of REbus are:

1. Power Distribution

2. Device Communications

Power Distribution
REbus nanogrid technology utilizes power curves on a
common high voltage DC bus to regulate the flow and
distribution of power depending on the selected system
mode and settings.
DANGER
Electrocution. Initiate a system-wide shutdown and turn the
PWRcell DC Disconnect Switch OFF on all connected
batteries before performing service. Failure to do so will
result in death, serious injury, or equipment and property
damage.
SAFETY INFORMATION: Always disable the system
before servicing. If the inverter or battery is enabled,
REbus voltage (360–420 VDC) will be present on all
connected REbus DC wiring! No other devices need
to be enabled or connected for voltage to be present
at the REbus terminals in the inverter or on con-
nected wiring. The inverter builds DC voltage on
REbus from its AC connection as soon as it has been
enabled from the inverter device page.
Best Practices
1. Wire Labeling
•
It is recommended to label each set of REbus
home run wires at both ends during installation.
2. Pre-commissioning Wiring Checks
•
Complete all pre-commissioning checks detailed in
the Commissioning Quick Start guide, packaged
with inverter, prior to energizing the inverter.
•
Performing all pre-commissioning checks is the
best way to avoid damaging equipment.
3. Inverter Control Panel
•
After energizing and enabling the inverter, confirm
the following on the Inverter Control Panel:
– Inverter Status LED is solid green.
– REbus DC voltage on the home screen displays
360-420 VDC.
Diagnostic Repair Manual
4. REbus Status LED
LED Color
Green
Yellow
Red
Troubleshooting
For REbus power lines troubleshooting see
PWRcell Inverter
Device Communications
Generac PV Links, PWRcell Batteries, and the PWRcell
Inverter utilize
bidirectional
Communications are achieved using Power Line Modem
(PLM) technology.
programmed to a channel between 1–12. If devices on a
given inverter system are programmed to different
channels, they will not be able to communicate with one
another.
(000600)
Best Practices
1. DC Disconnects
•
Ensure DC disconnects for connected devices are
in the ON position. In most cases REbus voltage
must be present on device wiring for Power Line
Communications.
NOTE: Due to its internal power source, the battery
cabinet can communicate without REbus voltage.
2. Polarity
•
Ensure REbus positive and negative wiring polarity
is correct at the inverter and all connected REbus
devices (PV Links and Batteries). Devices will not
communicate if polarity is reversed.
3. REbus Ground
•
Ensure each REbus device has an uninterrupted
ground connection between it and the inverter.
•
It is recommended to run a separate ground wire
for each REbus circuit.
NOTE: The ground wire for a circuit on REbus is
necessary to maintain common mode voltage on the
power lines
Communications.

Section 2 Understanding REbus

REbus Status
All devices are enabled and functioning
normally on REbus.
One or more devices are disabled, or no
devices are detected.
A serious fault has been detected on a
device or the REbus wiring.
section in this manual.
Power Line Communications
communication. Power
Each REbus device
for the system's
Table 4-1 in
for
Line
can be
Power Line
7