Distance Relay - 21L

  • GARD 8000 - Current Differential Relay thumb
  • GARD 8000 - Current Differential Relay thumb
  • GARD 8000 - Current Differential Relay thumb
GARD 8000 - Current Differential Relay

Product Description

Distance Protection Module - GARD 8000® System
The Distance Protection Module in the GARD 8000® System is a full-featured Line Distance Relay with all protection functions required for a complete line protection terminal. It can be used as a stand-alone Main protection, to provide channel independent back-up for the current differential protection, or operate in parallel with the Current Differential Module, providing an independent, different, measuring principle.

The Distance Protection Module has four measuring zones, where all zones can be set Forward or Reverse. A Reverse Zone 4 is used in pilot schemes and/or as a backup zone for bus faults behind the relay.

The Distance Protection Module can operate as a channel independent stepped distance relay or applied in a pilot scheme, selectable to permissive, unblocking or blocking. Weak infeed and transient block logic is included. The Distance Relay Module may use any communications interface in the GARD 8000® System. The channel interface can be dedicated to the Distance Relay or be shared with a Teleprotection System and/or a integrated Current Differential Protection Module.

Protection Features:

  • Distance (mho / quadrilateral for all 4 zones)
  • Overcurrent supervision
  • Overcurrent elements (instantaneous phase, ground, negative sequence)
  • Overvoltage / Undervoltage
  • Out-of-Step blocking
  • Load Encroachment
  • Loss of load
  • Close-into-fault
  • Fault locator
  • Loss-of-potential
  • Frequency elements / load shed functions
  • Recloser
  • Sync check
  • Voltage check
  • Breaker failure function
  • Breaker monitoring
  • Dual breaker applications
  • Plug-in Line Distance Protection in the GARD 8000® Protective Relay and Communications System
  • Use as a stand-alone Line Distance Relay or as a communications independent back-up for a GARD 8000® Current Differential Protection Module
  • Stepped Distance Protection or Distance Pilot Protection using the GARD 8000® System's communication interfaces which include audiotone, digital, fiber optic, or Power Line Carrier
  • Eliminates the need for external teleprotection channel devices for pilot communications
  • Eliminates relay-to-teleprotection wiring
  • Simplifies pilot protection system commissioning and configuration
  • 3U or 6U chassis depending on number of functional modules included
  • Dual breaker application by combining the distance relay with breaker modules
  • Synchrophasor measurement
  • Supports NERC/FERC security standards
  • 4 Zones, all 4 reversible
  • Phase-phase and phase-ground mho characteristic
  • Selectable quadrilateral characteristic
  • Built-in logic for permissive (PUTT, POTT, DCUB) and blocking (DCB) pilot schemes
  • Out-of-step block and trip
  • Loss-of-potential block
  • High-set and inverse time overcurrent elements
  • Breaker failure protection
  • Reclosing and synch check
  • Under- and overvoltage elements
  • Under-, over-, and rate-of-change frequency elements
  • Accurate Fault Locator
  • Digital fault records directly in COMTRADE
  • Optional Single Pole Trip Logic
  • 10 Year Warranty

AC Current Inputs

Nominal 1 or 5 A
Continuous 4 times nominal
One second 100 times nominal
Burden <0.2 VA for 5 A nominal
<0.05 VA for 1 A nominal


Frequency 50 or 60 Hz

Metering Accuracy

Voltages +/- 0.1% (60 - 300V)
Bias 5A nominal +/-2 mA/0.1% (0.5-160A)
1A nominal +/-0.5 mA/0.1% (0.1-30A)
Phase angle +/-0.3 deg
Power factor +/-0.001
Frequency +/-0.001 Hz
Active/reactive power (5A nominal and >1A load current)
0-180 deg 0.3%
+/-15 or 165 deg 0.5% active, 5% reactive
+/-45 or 135 deg 1% active, 1% reactive
+/- 75 or 115 deg 5% active, 0.5% reactive
+/-90 deg 0.3% reactive

Distance Elements

Zone 1 - 4 5A nominal
1A nominal
0.01 - 100 ohms
0.05 - 500 ohms
Resistive reach 5A nominal
1A nominal
0.01 - 100 ohms
0.05 - 500 ohms

Overcurrent Supervision Elements

5A nominal 0.20 - 7.50 A
1A nominal 0.04 - 1.5 A

Instantaneous/Definite Time Overcurrent Elements

5A nominal 0.10 - 150.00 A
1A nominal 0.02 - 30.00 A
Time delay 0.00 - 300.00 seconds

Directional Overcurrent Unit

Characteristic angle 0 - 90 deg
Minimum polarizing voltage 0.05 - 10.00 V
Negative or Zero sequence ground directional polarization

Time Overcurrent Elements

5A nominal 0.10 - 125 A
1A nominal 0.02 - 25 A
Time Dial ANSI: 0.5 - 10.00
IEC: 0.05 - 1.00
IEEE/US: 0.1 - 10
Definite time 0.05 - 300.00 sec
Moderately inverse
Very inverse
Extremely inverse
Long time inverse
Short time inverse
Inverse + maximum time
Very inverse + maximum time
Extremely inverse + maximum time
User defined

Under- and Overvoltage Elements

Pick-up range 20.00 - 300.00 V
Time delay 0.00 - 300.00 sec

Frequency Elements

Pick-up range 40.00 - 70.00 Hz
Undervoltage inhibit 20 - 150 V
Rate of change 0.5 - 10.00 Hz/s

Synchronism Check Elements

Voltage difference 2 - 30%
Phase angle 5 - 80 deg
Slip frequency 0.005 - 2.00 Hz
Time delay 0.05 - 300.00 s


No of shots 1 - 3
Dead-time 0.05 - 300 s
Reset time 0.05 - 300 s

Available Files

Files Available in the Customer Area

Please visit Operating Manuals or Product/Software Downloads to download relevant files. Requires RFL Customer Account.

Please visit Operating Manuals or Product/Software Downloads to download relevant files. Requires RFL Customer Account.

GARD 8000® Emulators

The RFL GARD 8000® Emulator will simulate a complete GARD Protective Relay and Communications system without the need for an actual GARD chassis. The Emulator will allow the user to pre-configure a system by selecting which RFL Modules are included in the final system, thus allowing for whole chassis configuration to be saved and loaded into an actual GARD chassis. Conversely files saved from an actual GARD chassis can be loaded into the Emulator. The Emulator will familiarize the user with the web driven capabilities of the GARD 8000® System and can be used as a teaching tool in the field. The GARD Emulator will show typical examples of GARD status situations. Note that because this is an emulator there are slight differences in menu options from an actual GARD chassis, also note that when the ‘Save’ button is clicked in configuration mode all configurations are accepted.

The Emulator Software is conveniently loaded into the users PC. The software, when loaded, also includes a user manual which will step you through using the Emulators. Examples of how the Emulator can interact with a GARD chassis are also described.

Please note that there are specific Emulators for the Image software that is loaded into the GARD 8000®, please download the correct version for your machine. Different versions do not work with different images.

If you should have any questions please call our Customer Service department at 973-334-3100 x226 and they will be glad to provide assistance.

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