Littelfuse PGR-8800 User manual

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Arc-Flash Relay
PGR-8800
PGR-8800
ARC-FLASH RELAY
REVISION 3-D-052923
Document Number: PM-1400-EN

PGR-8800 Arc-Flash Relay Rev. 3-D-052923
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TABLE OF CONTENTS
1 INTRODUCTION............................................................................................................7
1.1 Current-Supervised Arc-Flash Protection..................................................................7
1.2 Definite-Time Overcurrent Protection........................................................................7
1.3 Fail-Safe Operation ...................................................................................................7
1.4 Fast-Fault Location ...................................................................................................7
1.5 USB Interface............................................................................................................8
1.6 Scalable System .......................................................................................................8
1.7 Upstream Circuit Breaker Tripping............................................................................8
2 INSTALLATION..............................................................................................................9
3 POWER SUPPLY.........................................................................................................12
3.1 AC Supply ...............................................................................................................12
3.2 DC Supply...............................................................................................................12
3.3 Low-Voltage DC Supply ..........................................................................................13
3.4 External 24-V Battery Backup .................................................................................13
4. OPTICAL SENSORS ...................................................................................................14
4.1 PGA-LS10 Photoelectric Point Sensor with Sensor Check .....................................15
4.1.1 PGA-LS10 Connection .........................................................................................16
4.1.2 PGA-LS10 Installation ..........................................................................................17
4.2 PGA-LS20 and PGA-LS30 Fiber-Optic Sensor with Sensor Check ........................18
4.2.1 Fiber Connection ..................................................................................................18
4.2.2 Receiver Wiring Connections ...............................................................................18
4.2.3 Transmitter Wiring Connections ...........................................................................18
4.2.4 PGA-LS20 and PGA-LS30 Connection ................................................................19
5 SENSOR PLACEMENT.............................................................................................20
5.1 General Guidelines .................................................................................................20
5.2 Switchgear Protection .............................................................................................20
5.3 Transformer Protection ...........................................................................................20
6 CURRENT SENSORS .................................................................................................21
6.1 Current Inhibit Mode................................................................................................21
6.2 Overcurrent Protection............................................................................................21
6.3 Current Sensor Characteristics ...............................................................................22
7 DIGITAL INPUTS .........................................................................................................23
7.1 Inhibit ......................................................................................................................23
7.2 Trip..........................................................................................................................23
7.3 Reset.......................................................................................................................23
7.4 Circuit Check...........................................................................................................23
8 OUTPUTS ....................................................................................................................24
8.1 Online......................................................................................................................24
8.2 Service ....................................................................................................................25
8.3 Tripped....................................................................................................................25
8.4 Trip Coil...................................................................................................................27

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9 LED INDICATION.........................................................................................................29
10 PGR-8800 BUTTONS .................................................................................................29
10.1 Mode .......................................................................................................................32
10.2 Trip..........................................................................................................................32
10.3 Reset.......................................................................................................................32
10.4 Mode + Reset..........................................................................................................32
10.5 Mode + Trip.............................................................................................................32
11 LINK ............................................................................................................................33
11.1 Configuration...........................................................................................................33
11.2 Button Function.......................................................................................................33
11.3 Modbus Communication .........................................................................................34
12 USB INTERFACE .......................................................................................................35
12.1 Connecting to a PC .................................................................................................35
12.2 Configuration Software............................................................................................36
12.2.1 Configuration Software Tabs ......................................................................36
12.2.2 Configuration Software Buttons ..................................................................37
12.2.3 Default Configuration..................................................................................37
12.2.4 General Settings.........................................................................................38
12.2.5 Optical-Sensor Settings..............................................................................38
12.2.6 Current-Sensor Settings .............................................................................41
12.2.7 Digital-Input Settings ..................................................................................43
12.2.8 Output Settings...........................................................................................44
12.2.8.1 Online Output .........................................................................................44
12.2.8.2 Service Output........................................................................................45
12.2.8.3 Tripped Output .......................................................................................47
12.2.8.4 Trip Coil Output ......................................................................................49
12.2.9 Communications Settings...........................................................................52
12.2.10 Advanced Settings......................................................................................55
12.2.11 About Tab...................................................................................................56
12.3 Data Log Drive ........................................................................................................56
12.4 Firmware Upgrade ..................................................................................................58
13 COMMISSIONING ......................................................................................................59
13.1 Configuration of Installed Sensors ..........................................................................59
13.2 Testing the Sensors ................................................................................................59
13.3 Testing the Trip Coil ................................................................................................60
13.4 Full Operation Test (Online)....................................................................................60
13.5 Light Sensitivity Adjustment ....................................................................................61
13.6 Fiber-Optic Sensor Adjustment ...............................................................................61
13.6.1Sensor Adjustment for a Fiber Length other than 60 cm (24”) ............................61
13.6.2Sensor Adjustment in Small Compartments........................................................62
14 SPECIFICATIONS ......................................................................................................63
14.1 PGR-8800 ...............................................................................................................63
14.2 Sensors...................................................................................................................67

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15 ORDERING INFORMATION.......................................................................................68
16 WARRANTY ...............................................................................................................68
APPENDIX A PGR-8800 MODBUS RTU PROTOCOL .....................................................69
A.1 Protocol .......................................................................................................................69
A.1.1 Configuration Setup .......................................................................................69
A.2 Message Synchronization ...........................................................................................69
A.3 Error Checking ............................................................................................................69
A.4 Function Codes Supported..........................................................................................70
A.4.1 Read Input/Holding Registers (Code 04/03) ..................................................70
A.4.2 Write to Register ............................................................................................70
A.4.2.1 Write Single Register (Code 6) ...............................................................70
A.4.2.2 Write Multiple Registers (Code 16) .........................................................71
A.4.3 Exception Responses ....................................................................................71
A.5 PGR-8800 Database ...................................................................................................71
A.6 Specifications ..............................................................................................................71
APPENDIX B MODBUS COMMUNICATIONS DATABASE TABLE..................................72
APPENDIX C COORDINATED TRIPPING OF UPSTREAM BREAKERS ........................78
C.1 System Overview ........................................................................................................78
C.1.1 Circuit Breaker Feedback Detection ..............................................................78
C.1.2 Current Sensor Detection ..............................................................................78
C.1.3 Total Clearing Time .......................................................................................78
C.1.3.1 Arc Detection Delay................................................................................78
C.1.3.2 Circuit Breaker Operating Time ..............................................................79
C.1.3.3 Output Delay ..........................................................................................79
C.1.3.4 Total Clearing Time Examples................................................................79
C.1.4 Relay Output .................................................................................................79
C.1.5 Link Output ....................................................................................................79
C.1.6 PGA-1100 Diode Logic Unit ..........................................................................80
C.2 Application and Configuration .....................................................................................80
C.2.1 Single PGR-8800 Configuration ....................................................................80
C.2.2 Dual PGR-8800 Configuration using Link Interface .......................................84
C.2.3 Single PGR-8800 Configuration with Current Sensor Input...........................85
C.2.4 Dual PGR-8800 Configuration using Link Interface and
Current Sensor Input......................................................................................90
C.2.5 Configuration of Multiple Inputs and Outputs.................................................93
C.2.6 Tripping Common Upstream Circuit Breaker from Several Zones
using PGA-1100.............................................................................................94
APPENDIX D SYSTEM PARAMETERS AND SETUP RECORD......................................95
APPENDIX E PGR-8800 REVISION HISTORY ..............................................................100

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LIST OF FIGURES
1 PGR-8800 Outline and Mounting Details ......................................................................9
2 PGR-8800 Typical Wiring Diagram .............................................................................10
3 PGR-8800 24-Vdc Source Typical Wiring Diagram.....................................................11
4 Local Sensor Detection Zone for a 3 kA Fault.............................................................14
5 PGA-LS10 Detection Range for a 3 kA Fault ..............................................................15
6 PGA-LS10 Connection Diagram .................................................................................16
7 PGA-LS10 Mounting Detail .........................................................................................17
8 PGA-LS20 and PGA-LS30 Connection Diagram ........................................................19
9 LED Flash Patterns .....................................................................................................29
C.1 Single PGR-8800 Application .......................................................................................81
C.2 Dual PGR-8800 Configuration using Link Interface.....................................................84
C.3 Single PGR-8800 Configuration with Current Sensor Input.........................................86
C.4 Dual PGR-8800 Configuration using Link Interface and
Current Sensor Input ..................................................................................................90
C.5 Tripping Common Upstream Circuit Breaker from Several Zones
using PGA-1100 ..........................................................................................................94
LIST OF TABLES
A.1 Read Registers (Code 04/03) .....................................................................................70
A.2 Write Single Register (Code 6) ...................................................................................70
A.3 Write Multiple Registers (Code 16) .............................................................................71
C.1 Circuit Breaker Operating Times.................................................................................79

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INTRODUCTION
The PGR-8800 Arc-Flash Relay is a high-speed, arc-detection device for electrical power-distribution
systems. The PGR-8800 has one local sensor and supports both point and fiber-optic sensor
technologies for optical arc detection. There are inputs for six optical sensors and three current
sensors.
On the occurrence of an arc fault, the PGR-8800 detects the fault and pulses the trip contact in less
than one millisecond. The tripping pulse is typically used to trip the circuit breaker(s) supplying the
circuit. The total arcing time is effectively reduced to the mechanical opening time of the circuit
breaker; typically between 30 and 75 milliseconds. The trip contact is a solid-state switch (IGBT),
which provides fast reaction and sufficient drive capability for circuit-breaker trip circuits.
Using optical sensors rather than relying strictly on current measurement allows a much faster
detection time than overcurrent relays or a circuit breaker alone can typically provide. This will lower
the incident energy of an arc flash and increase worker safety, reduce fault damage, and improve
uptime. Since the incident energy is decreased, the level of personal protective equipment (PPE)
required may also be lowered, subject to an arc-flash study modeling the system parameters.
The MODBUS RTU protocol is implemented in the PGR-8800. This will provide status information
for sensors, analog inputs, digital inputs, digital outputs, and numerous event and error flags. It also
provides the ability to remotely reset the PGR-8800. See Section 11.3 and Appendices A and B.
The PGR-8800 can be used on any electrical system with any voltage (ac or dc) and can be powered
from either an ac or dc supply, or both. If it is powered from line supply, it can charge a backup
battery to power the PGR-8800 when the line supply is lost.
1.1 Current-Supervised Arc-Flash Protection
The PGR-8800 has three phase-current inputs which can be used to prevent optical trips when the
measured current is below a user-specified level. This makes it possible to avoid nuisance tripping
from external light sources such as lightning or welding arcs.
1.2 Definite-Time Overcurrent Protection
Using the phase-current inputs, the PGR-8800 can be configured to trip on overcurrent, with a
minimum reaction time of one millisecond. There are two user-adjustable levels of overcurrent
protection with independent trip times to coordinate with other protective devices. This provides
protection from long-lasting overload conditions and fast reaction to overcurrent even when no arc
is detected.
1.3 Fail-Safe Operation
The PGR-8800 continuously monitors its internal circuitry as well as the connected optical sensors.
Any system faults, including a sensor-cable fault, are indicated by a flashing LED and can be logged.
A redundant trip circuit ensures that the PGR-8800 will trip on an arc flash even if a primary trip-
circuit component fails. The solid-state design of the redundant trip circuit also provides a
significantly faster response to an arc on power-up (for example, after maintenance during a
shutdown) than is possible with microprocessor-only relays.
1.4 Fast-Fault Location
The optical sensors used with the PGR-8800 include LED indication of health and, if it has detected
an arc flash, of fault location. The PGR-8800 also has one LED per optical sensor to indicate which
sensor(s) have caused a trip.

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1.5 USB Interface
A USB interface on the front of the PGR-8800 provides easy PC access to configuration settings
and access to an event log which provides detailed diagnostic information about measurements
before and after a trip. No PC driver or software installation is required.
1.6 Scalable System
Up to four PGR-8800 modules can be connected into a single system, allowing a total of 24 optical
sensors per system. Each PGR-8800 can be programmed to have up to 4 independent trip zones,
providing flexibility to fit various tripping schemes on larger systems.
1.7 Upstream Circuit Breaker Tripping
The PGR-8800 can be configured to trip an upstream circuit breaker as a backup to local circuit-
breaker failure. Circuit-breaker failure can be detected with a discrete input (such as a local circuit
breaker feedback signal), current measurement, or the Link function. See Appendix C for more
information.

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2 INSTALLATION
The PGR-8800 can be surface mounted using four 5-mm (10-32) screws, or it can be DIN-rail
mounted using the optional mounting brackets (PGA-0031).
Ensure there is enough clearance around the module to allow the plug-in terminals to be removed
and inserted.
Do not install modules which have been damaged in transport.
See the PGR-8800 Arc-Flash Relay Application Guide for additional installation information.
NOTE: The PGR-8800 includes an internal non-rechargeable battery that powers the real-time clock.
Please consult local regulations regarding the use of batteries in electrical equipment. The battery is
not designed for user service or removal; please contact Littelfuse with any questions regarding
battery removal.
FIGURE 1. PGR-8800 Outline and Mounting Details.

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FIGURE 2. PGR-8800 Typical Wiring Diagram.

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FIGURE 3. PGR-8800 24-Vdc Source Typical Wiring Diagram.

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3 POWER SUPPLY
The PGR-8800 Arc-Flash Relay can be powered from an ac or dc supply, or both. However, only
one source can be connected to terminals 31 and 32.
3.1 AC Supply
Connect an ac supply to terminals 31 and 32. The supply voltage must be 100 to 240 Vac.
3.2 DC Supply
Connect a dc supply to terminals 31 and 32, ensuring correct polarity. The supply voltage must be
110 to 250 Vdc.

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3.3 Low-Voltage DC Supply
Connect a dc supply to terminals 34 and 36, ensuring correct polarity. The supply voltage must be
14 to 48 Vdc. This input will not charge the backup battery.
3.4 External 24-V Battery Backup
Connect a 24-Vdc battery to terminals 35 and 36, ensuring correct polarity. The PGR-8800 will only
charge the battery when there is rated voltage on power-supply terminals 31 and 32 (ac or dc). The
PGR-8800 supplies a constant-current, constant-voltage (CCCV) of 27 V with no load and maximum
available current of 200 mA. A sealed lead-acid battery with a capacity between 2 and 15 Ah, such
as a pair of Panasonic VRLA LC-R122R2P, should be used and exchanged regularly according to
the manufacturer’s recommendations.
If the PGR-8800 is supplied by the backup battery and the battery voltage drops below 20 V, the
PGR-8800 will shut down to protect the battery.
Do not combine external battery backup and the low-voltage DC supply. The DC supply will not
charge the battery.
NOTE: Arc monitoring is disabled when the PGR-8800 is powered down.

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4 OPTICAL SENSORS
The PGR-8800 has one local sensor and six inputs for external optical sensors. The local sensor is
primarily used for commissioning and can also be enabled for arc-flash protection. Its light-detection
zone is illustrated in the diagram below.
FIGURE 4. Local Sensor Detection Zone for a 3 kA Fault.
Two external sensor types are supported:
•PGA-LS10 Photoelectric Point Sensor with sensor check
•PGA-LS20 and PGA-LS30 Fiber-Optic Sensors with sensor check
The sensors can be used together, in any combination.
Both sensor types have LED indication of sensor health and fault location. A sensor-check circuit
tests the sensor to verify that the sensor assembly is functioning correctly. A healthy sensor will
indicate two fast flashes of its internal red LED every few seconds. A sensor that has detected an
arc will slowly flash red.
The sensors connect to the PGR-8800 with shielded three-wire 20 AWG (0.5 mm2) electrical cable.
Each sensor includes 10 m (33 ft) of cable which can be shortened or extended up to 50 m
(164 ft).These cables should be considered to be at ground potential when determining electrical
clearances in the cabinet.
Any connected optical sensor with circuit check will be automatically detected and cause the
PGR-8800 to report an error if it is subsequently disconnected.
PGA-LS10 PGA-LS20 / PGA-LS30
NOTE: Inserting and removing sensor cables can cause a trip depending on which terminals make
contact first. Always place the unit in service mode before connecting and disconnecting sensors.

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4.1 PGA-LS10 Photoelectric Point Sensor with Sensor Check
This sensor has a detection area of a 2-m (7 ft) half-sphere for arcs of 3 kA or more.
A built-in LED enables the PGR-8800 to verify the function of the light sensor, wiring, and electronics.
If the sensor does not detect the sensor-check LED, a sensor-fail alarm will occur -- the ONLINE
output will change state and the ONLINE LED will begin to short flash. See Section 9.
The sensor includes 10 m (33 ft) of shielded three-wire electrical cable which can easily be shortened
or extended to a maximum of 50 m (164 ft). The following AWM styles (or equivalent) can be used:
•Style 2464, 20 AWG, 80 C rated, 300V, 3-conductor with shield
•Style 1316, 20 AWG, 105 C rated, 600V, 3-conductor with shield
•Style 21819, 20 AWG, 105 C rated, 600V, 3-conductor with shield
FIGURE 5. PGA-LS10 Detection Range for a 3 kA Fault.

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4.1.1 PGA-LS10 Connection
FIGURE 6. PGA-LS10 Connection Diagram.

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4.1.2 PGA-LS10 Installation
The PGA-LS10 point sensor includes an adhesive-backed drill template for easy surface or panel-
mount installation.
FIGURE 7. PGA-LS10 Mounting Detail.

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4.2 PGA-LS20 and PGA-LS30 Fiber-Optic Sensors with Sensor Check
The PGA-LS20 and PGA-LS30 have a 360° detection zone along the fiber’s length. A built-in LED
enables the PGR-8800 to verify the function of the light sensor, wiring, and electronics. If the sensor
does not detect the sensor-check LED, a sensor-fail alarm will occur -- the ONLINE output will
change state and the ONLINE LED will begin to short flash. See Section 9.
The PGA-LS20 and PGA-LS30 sensors have three components:
1. A fiber-optic cable, with one end covered with a black sleeve. The PGA-LS20 has 8 m
(26 ft) of active fiber and 2 m (7 ft) of covered fiber. The PGA-LS30 has 18 m (59 ft) of active
fiber and 2 m (7 ft) of covered fiber.
2. A transmitter with a white enclosure and a white thumb nut.
3. A receiver with a white enclosure, a black thumb nut, and an adjustment screw behind an
access hole.
Both the receiver and the transmitter connect to one PGR-8800 input using shielded three-wire
electrical cable. All three components are monitored to ensure correct operation.
4.2.1 Fiber Connection
The fiber is the light-collecting element of the PGA-LS20 and PGA-LS30. It must be installed so it
has line-of-sight to all current-carrying parts. In some cases this may be accomplished by following
the bus bars along the back wall of the cabinets.
Drill holes using the included drill template and fasten the transmitter and receiver to the cabinet
walls using rivets or screws. Connect the attached cables to the PGR-8800. The wires of the
transmitter and receiver must be connected as shown in Fig. 8.
Connect the black-sleeve-covered end to the receiver using the black thumb nut, and the white
uncovered end to the transmitter using the white thumb nut.Ensure the fiber is inserted completely
into the transmitter and receiver and the nuts are tightened. Pull gently on the cable to verify a secure
connection. The maximum pull strength of the fiber is 30 N (6.7 lbf).
The fiber should not be sharply bent or pinched. The minimum bending radius is 5 cm (2”). Ensure
that any drilled holes are free of any sharp edges or burrs. Use grommets for further protection.
NOTE: Removing the fiber from the transmitter end only can cause a trip if the end of the fiber is
pointed towards a light source, since the fiber conducts light. When servicing the arc flash relay,
always place the unit in service mode before connecting and disconnecting sensors and fibers.
4.2.2 Receiver Wiring Connections
Connect the red wire to 5V.
Connect the yellow wire to RX.
Connect the white wire and the shield to 0V.
4.2.3 Transmitter Wiring Connections
Connect the red wire to 5V.
Connect the white wire to TX.
Connect the shield to 0V.
The yellow wire is not used.

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4.2.4 PGA-LS20 and PGA-LS30 Connection
The sensor is shipped with the wires mounted in a terminal block. See Fig 8.
The transmitter and receiver include 10 m (33 ft) of shielded three-wire electrical cable which can be
shortened or extended up to 50 m (164 ft). Transmitter and receiver cables can be different lengths
and must be independently shielded. The following AWM styles (or equivalent) can be used:
•Style 2464, 20 AWG, 80 C rated, 300V, 3-conductor with shield
•Style 1316, 20 AWG, 105 C rated, 600V, 3-conductor with shield
•Style 21819, 20 AWG, 105 C rated, 600V, 3-conductor with shield
Failure to independently shield transmitter and receiver cables can lead to an incorrect circuit check
– a faulty sensor could be falsely detected as continuous. However, if there is no sensor fault, arc-
flash detection will function normally in this condition.
FIGURE 8. PGA-LS20 and PGA-LS30 Connection Diagram.

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5 SENSOR PLACEMENT
5.1 General Guidelines
Optical sensors require line-of-sight to points being monitored. Ensure that the point sensors and
fiber are not blocked by fixed or moveable objects. Areas that will be accessed for maintenance or
with moveable parts (such as draw-out circuit breakers) should be considered a high priority for
installation. Do not place sensors or cables on bare components that will be energized and avoid
sharp bends in the cable, particularly when using the PGA-LS20 and PGA-LS30 fiber-optic sensors.
The electrical cables and sensors should be considered to be at ground potential when determining
electrical clearances.
Sensors should be mounted in a location that will minimize the chance of debris or dust build-up and
with easy access for maintenance if needed. A point sensor mounted at the top of an enclosure and
facing down is optimal for reducing dust build-up. It should be noted that most enclosures are metallic
and the reflectivity combined with the high intensity of an arc mean that even a dirty sensor will
collect adequate light.
Sensors can be tested individually by putting the PGR-8800 into service mode by pressing the
MODE button and shining a bright light on the sensor. A trip will be indicated if the sensor detects
the light, but a trip signal will not be sent to the circuit breaker. If the LED on the sensor or relay isn’t
indicating a trip, cleaning is necessary. Note that in service mode, the PGR-8800 will not trip if an
arc flash occurs. Remember to return the PGR-8800 to online mode after testing is completed. In
dusty environments, sensor cleaning should be part of a regular maintenance schedule and can be
performed using compressed air or a dry cloth.
5.2 Switchgear Protection
The sensors used for arc-flash detection are optical sensors. Line-of-sight between the points where
an arc could occur and the sensor is crucial.
Often one point sensor is sufficient to monitor a complete switchgear compartment. However, if there
are large components such as circuit breakers that cast shadows over wider areas, more than one
point sensor is required.
5.3 Transformer Protection
The PGR-8800 can also be used for the protection of transformers. Two or more point sensors
should be used per transformer to monitor the primary and secondary connection terminals. For the
placement of the sensors, the same considerations apply as for switchgear protection.