Paralleling Switchgear (PSG)
GE Zenith Capabilities - Overview
GE Zenith Controls – Paralleling Switchgear (PSG)
• First system
built in 1975
• Currently ~ 150
systems/year
• Currently
building project
#1280
2
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What is a Paralleling Switchgear System (PSG) ?
Controls and switchgear, acting as a system, to manage & distribute emergency
power and/or reduce energy costs thru intelligent use of local generation
Genset #1
Genset #2
Genset #3
Utility
Breaker
Primary
Source
(Normally
Energized)
Service
Entrance
Breaker
Normal
System
(Normally
Energized)
Paralleling
Breaker
Paralleling Bus
Distribution
Breakers
(Normally Deenergized)
ATS
Exit
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Emergency
System
Critical Loads
Key Benefits of PSG?
• Increased Backup Power Supply Capacity
– When backup supply needs are > capacity 1
Gen
• Backup Supply Redundancy
4
– Provides “N + 1,2,etc” redundancy. Critical loads
not reliant on only 1 Genset
• Operational Flexibility
– Ability to switch loads between multiple sources
(including Gensets) for maintenance & test
without interrupting power to the loads
• Reduced Energy Bills
– Turn on-site generation capability into an moneysaving Asset, with start/stop/loading intelligence
for reduced energy & demand charges.
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Typical Systems built by GE Zenith Controls
• Single Genset – Single Utility Soft Load Transfer
Switch
For small facility standby & distributed
generation
• Multiple-Genset Standby
5
For Life Safety or Business Critical standby
power to selected high-priority loads.
• Utility Paralleling, Peak Shaving
Paralleling of Generator(s) and Utility supplies
for backup of entire facility and reduced energy
charges.
• Mission Critical Standby
Turning on-site generation capability into an
Asset, with start/stop/loading intelligence for
reduced energy & demand charges.
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Examples of Typical GE
Zenith Systems
Type 1 – Single Gen, Single Utility Soft Load Transfer
Switch
Soft Load Transfer Switch
Single Gen, Single Utility Architecture
Utility
Supply
Building
Dist. System
Speed Control
Generator
Engine
Gen Supply
Breaker
GCB
(N/O)
Utility Supply
Breaker
MCB
(N/C)
Standby
Generator
Building
Load
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Sequences of Operation – Softload Transfer Switch
Mode:
GCB
Genset/Backup
Supply
Critical
Load
MCB
Gen
Status:
Normal
OFF
Energized.
kW Varies.
kW = Facility
Load
Standby
Running.
kW Varies.
kW = Facility
Load
Failed/Off.
Running.
Soft
Re-Transfer Initial kW =
Facility Load
To Utility
Running.
Initial kW=
0kW
Utility/Primary
Supply
kW
kW
GCB
MCB
Final kW=
~10% Rated
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Utility
Status:
Final kW=
Facility Load
Baseload
Setpoint
Time
GCB
kW Level
kW Level
Sequences of Operation – Softload Transfer Switch
Mode:
Time
MCB
kW Level
kW
Running.
kW Fixed.
kW = Preset/
Fixed
(typically
80-100%
Genset
Capacity)
Energized.
kW Varies.
kW = Facility
Load in excess
Of Fixed
Gen kW
Import
(Export)
Mode
Running.
kW Varies.
kW = Facility
Load in excess
Of Import
Setpoint
Energized.
kW Fixed.
kW = Fixed
Import or
Export
Level (kW)
kW
kW Level
kW Level
Time
Time
GCB
kW Level
kW
10
Time
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Time
MCB
kW
kW
Utility
Status:
Base
Load
Mode
kW
Import
Setpoint
Gen
Status:
Control Panel – Softload Transfer Switch
GENERATOR
UTILITY
LAN/
WAN
Generator & Utility
Protection via:
GE Multilin G30 ™
G30
Peak Shaving Control via:
GCP
GW4
Woodward GCP-32 ™
Peak Shaving Controller
communications via:
Local Monitoring and email
Alarm transmission via:
Enervista Viewpoint
Monitoring ™
Woodward GW4 ™
(Modbus)
Plus:
Manual Control Switches
Safety Lockout/86 Relay
LED Status Annunciation
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Site Level: Peak Shave System Metering
Meter #1: Utility Meter (UM) : Utility Supply kW, Energy, etc.
Meter #2: Generator Meter (GM) : Generator Supply kW, Energy, etc.
Virtual Meter #1: Load Meter (LM = GM + UM) {Developed in GE Aggregator ™}
Peak Shaving Savings = (LM * Rate Structure) – (UM * Rate Structure)
GE Multilin G30 Relay
Meter #1:
Generator
Source
Metering
(GM)
Meter #2:
Utility
Source
Metering
(UM)
V (PT’S)
3 CT’s
3 CT’S
V (PT’S)
Closed Transition
ATS or 5-cycle CB’s
Engine
Generator
GCB
MCB
Genset
Supply
Critical
Load
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Utility
Supply
Peak Shave Savings Reports – GE Aggregator™
1
Setup Utility billing
structure
Export reports for
printing, sending,
or filing
2
Setup custom site
bills (showing
usage or savings)
4
3
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Enter Begin &
End dates &
create/ view bills
Local & Remote Access to Reports
LEVEL 4: Enterprise
Energy Aggregator™
Viewers
(Up to 5 concurrent users)
Web
Serv
er
View reports from
EEA.
“Aggregates”, or
combines date from
from the (6) REA
servers.
…
Up to
~ 100 Sites
per Aggregator
Est. (6) REA’s for full
630-site configuration
Local data-logging by
Multilin G30’s
GENERATOR
UTILITY
GENERATOR
G30
GCP
UTILITY
G30
GW4
GCP
GW4
(Qty. 1)
LEVEL 2: Regional
Energy Aggregator™
(REA)
(1 Server/~100 Sites)
LAN or VPN
Upload Data-Logs
LEVEL 3: Enterprise
Energy Aggregator™ (EEA)
Site Level
Site Peak Shaving
Control Systems w/ local
GE Enervista
Viewpoint™
Unlimited # Sites
GE Zenith ZTSSL
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GE Zenith ZTSSL
GE Zenith Design Recommendations
• True PQ Metering of Both Sources, including Waveform and
Events Capture – for quick diagnosis of system events and
outages
• Utility grade protective relaying for equipment and personnel
safety - – due to extended nature of utility paralleling.
• Open protocol Modbus communications for easy facility
integration
• Plug-and-Play PC Monitoring for low cost, but effective system
monitoring and alarm management, including automatic email
generation of any/all alarm events
• Key-lockable Control Switches for safety
15
• Automatic report generation for: Utility and Generator Energy
supply (kWH), Demand (kW), and Peak Shave savings (based on
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site-specific
utility rate structure).
Automatic
Transfer Switch
Product Training
Type 2 – Multiple Genset Standby
Multiple Genset Standby
Typical Architecture
Genset #1

Genset #2
Primary
Distribution
Genset #3
Paralleling
Bus
Secondary
Distribution
Emergency
Panelboard
ATS
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Emergency
Loads
Exit
Typical Sequence of Operation for PSG – On loss of Utility
X
Genset #2
Genset #1
Synchronous Conditions
1) Volts within
+/- 10%
1
Paralleling
Bus
2) Phase within
+/- 20 Deg
1
2
ATS
1
Utility Supply Fails
2
ATS Send start signal to all Gens
3
All Gens start. PSG control system
monitors. 1st Gen at rated Volts &
Freq is connected to the Paralleling
Bus.
Priority 1 ATS Xfer to Gens. PSG
inhibits xfer of lower priority ATS
to prevent Gen overload.
4
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5
6
7
8
PSG Controls synchronize 2nd and 3rd Gensets
to Bus (speed and volts bias to Gen Gov &
AVR), and close CB’s at point of synchonism
(see above).
PSG Controls remove xfer inhibits on lower
priority ATS to permit connection to Gen
system.
PSG Controls shed low priority ATS if Gens are
overloaded. PSG permits manual or auto reconnect.
PSG Controls shed low priority ATS if Gens
are overloaded. PSG permits manual or auto
re-connect.
Typical Sequence of Operation for PSG – On Return of Utility

Genset #2
Genset #1
Paralleling
Bus
ATS
1
Utility Supply Returns
4
2
ATS’s retransfer loads to Utility,
after preset time delays, and
remote start commands.
PSG controls hold start signal to all Gens to
permit cooldown at no load.
5
After cooldown timer expires, PSG controls
remove start signals to Gensets.
3
When last ATS removes start
command, PSG Controls open all
Gen CB’s
6
Gensets shut down and remain ready for next
utility outage.
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Typical GE Zenith Configuration
Other key items (inside)
Key Items – GE Recommendation
1. GE Fanuc PLC (Single or
Redundant)
2. Flexible Woodward SPMA
(sync) and LSM (load Sharing)
modules
3. Hardwired backup switches for
load add/shed
4. Backup 24 VDC power supply
for system ride-thru on DC
control power problems
• Highly visible, LED Annunciation for instant viewing and viewing from
distance
• Full manual paralleling control switches (Auto/Manual, Sync Switch, CB
Open/close, Synchroscope/V/Hz meters on swing panel)
• Generator Analog Metering for best viewing of Gen & Utility stability
• Generator
Protective
Relay
(typically
grade for MV,
Industrialcapability
grade for
Totalizing Power
Quality
Meter
(PQM)Utility
with waveform
& diagnostic
• LV)
Simple Operator Interface Panel (OIP) for setup of time delays, load
add/shed, etc.
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Type 3 – Utility Paralleling, Peak Shaving
Utility Paralleling, Peak Shaving
Typical Architecture
Utility Supply
Genset
Breakers
Main Bus
Feeder Breakers
Facility Loads
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1. Generators sized to
high% of total facility
loads
2. Utility CB and Gen CB’s
act as a “Transfer
Switch”, switching 2
sources of power to main
bus in event of Utility
outage.
3. Re-transfer to utility
either Open or Closed
Transition (typically
closed)
4. Main bus is fed from 2
sources power – utility
supply (primary) and
generator supply
(backup)
5. Bus AIC/Short circuit
rating sized to capacity
Genset Base Load:
Utility kW
Level
Gen kW
Level
Utility Paralleling - Base Loading
Baseload
Setpoint
Time
Utility Supply
1
Utility Supply Available
2
When pre-programmed
conditions for Genset starting
satisfied (Utility load >x, time of
day, etc) PSG Controls start
Gensets, synchonize to utility
supply, and close Gen CB’s.
3
PSG system controls kW on
Gensets to fixed, base load level.
4
5
As system load varies, Utility
supply kW varies to supply the
load.
When Gen supply no longer
needed, PSG Controls slowly ramp
load back to utility supply and open
Gen CB;s at near no-load.
5
PSG controls cooldown and
shutdown Gensets.
kW
Time
GCB
kW
GCB
kW
Load kW
Level
kW
Time
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kW
Utility kW
Level
Utility Paralleling - Import/Export
Baseload
Setpoint
Gen kW
Level
Time
MCB
Utility
Import/Export:
1 Utility Supply Available
2
When pre-programmed
conditions for Genset starting
satisfied (Utility load >x, time of
day, etc) PSG Controls start
Gensets, synchonize to utility
supply, and close Gen CB’s.
3
PSG system controls kW on
Gensets to maintain fixed kW
value on Utility supply (import or
export).
As system load varies, Genset
supply kW varies to supply the
load.
When Gen supply no longer
needed, PSG Controls slowly ramp
load back to utility supply and open
Gen CB;s at near no-load.
kW
Time
GCB
kW
GCB
4
kW
Load kW
Level
kW
Time
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5
5
PSG controls cooldown and
shutdown Gensets.
Typical GE Zenith Configuration
Other key items (inside)
Key Items – GE Recommendation
25
1. GE Fanuc PLC (Single or
Redundant)
2. Flexible Woodward SPMA
(sync) and LSM (load Sharing)
modules
3. Hardwired backup switches for
load add/shed
4. Backup 24 VDC power supply
for system ride-thru on DC
control power problems
• Highly visible, LED Annunciation for instant viewing and viewing from
distance
• Full manual paralleling control switches (Auto/Manual, Sync Switch, CB
Open/close, Synchroscope/V/Hz meters on swing panel)
• Full, Open transition, manual control of Utility CB
• Generator Analog Metering for best viewing of Gen & Utility stability
• Generator
Protective
Relay
(Utility
grade)
Totalizing Power
Quality
Meter
(PQM)
with waveform & diagnostic capability
• Industrial Computer with graphical 1-lines, load controls, trending,
alarm
management.
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Type 4 – Mission Critical Standby
Mission Critical Standby
Typical Architecture – Tier 4 Data Center
System ‘A’ Gen Bus
System ‘B’ Gen Bus
System ‘A’
Utility Bus
System ‘B’
Utility Bus
Gen A
Util A
Unit Subs
Util A
Util B
Gen B
Unit Subs
Unit Subs
Gen B
Util B
Gen A
Unit Subs
27
1. Complete system redundancy – Tier 4 classification
2. 100% Backup Generator N+1 capacity
3. 2 x Independent Gen Paralleling systems, each capable of 100% backup &
control of other system (GE Zenith-Fanuc unique design for Quadruple
GE
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redundancy!
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Typical GE Zenith Configuration
Util ‘B’
Util ‘A
Gen ‘A’
Gen ‘B’
Key Items – GE Recommendation
• Full Manual backup, visible LEDs, Utility Grade relaying, PQ Metering
• Synchronized-backup PLC each Gen System (2 x PLC each Gen system)
• Gen System Graphical Display, + large monitor each system for display
downstream load status
• Each System Master control capable backup of other system
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ZDEC 2020
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