Backup Modes Of Operation; Introduction; Abbreviations; Documents - Generac Power Systems PowerManager 004975-2 Manual

Operation
The function of the permissive and load shed relays is described
in the section labeled "System Settings". The "All generators
online status" relay indicates when all generators are online. The
"Exercise with transfer" relay indicates that an exercise with trans-
fer has been started. This signal should be used with GTS or third
party transfer switches to initiate a transfer, it is NOT REQUIRED
for the manufacturer's STS or MTS type transfer switches. The
state of all these relays can be viewed via the touchscreen status
page of via the main mimic panel of Genlink (figure 2.1).
3.11 BACKUP MODES OF
OPERATION

3.11.1 INTRODUCTION

The manufacturer's Modular Power System (MPS) is a system of
up to ten generators connected together performing as one unit.
It is designed to include a high degree of reliability. The integrated
control system is made up of components that are designed and
manufactured for compatibility. The enhanced reliability provided
by the backup modes described in this document ensures the
critical loads stay energized throughout the duration of a power
outage.

3.11.2 ABBREVIATIONS

ATS Automatic Transfer Switch
Bus Common Generator Power Bus or Emergency
Power Bus
MPS Modular Power System
PM-PC PowerManager® Parallel Controller
PM-SC PowerManager® System Controller
PM-PLS PowerManager® Backup Permissive/Load Shed
Controller

3.11.3 DOCUMENTS

P/N 0F8444 Technical Manual PowerManager® Digital
Control Platform (PM-DCP)
P/N 0F8671 PowerManager® Parallel Controller (PM-PC)
P/N 0F1076 PowerManager® System Controller (PM-SC)
P/N 0F8111 Single Line Diagram - MPS with PM-SC
P/N 0F8112 Single Line Diagram - MPS with PM-SC and
PM-PLS
PM-SC
ATS
10
Figure 3.9 — MPS Standard Control System
Gen 1 Gen 2 Gen 3 Gen 4
PM-SC PM-SC PM-SC PM-SC
P/N 0F9326
P/N 0F9326A

3.11.4 STANDARD CONTROL SYSTEM

The standard control system consists of a PM-PC for each genera-
tor and one PM-SC (Figure 3.9). The PM-SC controls and monitors
the PM-PC(s) via the RS-485 Generator Communications Bus. The
PM-SC uses commands to control the starting of the generators,
connecting/synchronizing the generators to the bus, proportion-
ally share load across all connected generators, disconnect the
generators from the Bus, and shut the generators down. The
PM-SC also accumulates data from the generators to support the
Remote Annunciator Panel(s) and other data displays. In addition,
the PM-SC issues Permissive signals and Load Shed signals to
control the system load.

3.11.5 NORMAL MPS OPERATION

The MPS is a system of generators performing as one unit when
all the PM-PC and PM-SC key switches are in the AUTO position.
The ATS(s) determine when the utility voltage is lost or becomes
invalid. The ATS(s) indicate to the PM-SC that the generators are
needed by activating a remote start signal. The PM-SC sends out
a start command to all the generators. The generators start and
indicate to the PM-SC when they are ready for power loading. The
PM-SC commands the first generator that is ready for load to con-
nect to the Bus. The PM-SC commands the remaining generators
to synchronize and connect to the Bus as they become ready for
load. As enough power becomes available on the Bus, the PM-SC
activates Permissive signals to the appropriate ATS(s) accord-
ing to the customer defined sequence of operation. As the Bus
becomes loaded, the PM-SC distributes the load proportionally to
the connected generators based on the generator's power capac-
ity while maintaining the target voltage and frequency. The ATS(s)
determine when the utility voltage has returned, they switch back
to utility, and then they indicate to the PM-SC that the generators
are no longer needed by deactivating the remote start signal. The
PM-SC sends out a command to all the generators to disconnect
from the Bus and enter their cooldown mode. The generators
shutdown after completing their cooldown period.
If there are not enough generators are available to handle the cur-
rent system load, the PM-SC activates Load Shed signals to the
appropriate ATS(s) or other devices according to the customer
defined sequence of operation and wiring.
Gen 5 Gen 6 Gen 7 Gen 8
PM-SC PM-SC PM-SC PM-SC
WD-PLS Interconnection Diagram - MPS-
Gemini Only
WD-PLS Interconnection Diagram - MPS-Non
Gemini
Remote
Annunciator
Panel
Gen 9 Gen 10
PM-SC PM-SC