AC Ground Fault Selective Relay
for Rectifier
Over Current Relay For AC Cable Ground(Product name: 50GSR)
This device detects ground faults in substations for DC electric power lines.
Protects against AC line ground faults between the rectifier transformer and therectifier, which had insufficient protection in a conventional manner.
This device detects the third harmonic component in the earth fault current.

AC circuit

Rectifier transformer(SR-Tr)

Protection range of 50GSR

R
phase
T
phase

Rectifier(SR)

DC circuit

DC bus barS
phase

Exterior(sheath)

Cu Shielding
layer

insulatorFault
Detects third harmoniccomponents included
in ground fault current
Fault
current

DetectingunitRailTime
Relay section

AC ground-fault selective relay forrectifier (50GSR)

Substation grounding

earth fault current

Purpose and role of equipment
When a ground fault occurs due to cable insulation breakdown in the AC line between the rectifiertransformer (SR-Tr) and the silicon rectifier (SR), the ground fault may not be detected dependingon the resistance value of the ground fault point, and the ground fault may continue, leading tofire or equipment failure. Therefore, the development of a protective relay that detects ground
faults has been desired.

Fault current detection by 3rd harmonic
As a result of conducting transient simulations and artificial fault tests using actual facilities, we
discovered that ground fault currents have been including third harmonic components, which do
not occur in a healthy state, flow in the cable ground wire when a ground fault occurs, and wedeveloped a device that can detect such currents.
If the resistance of the ground fault point is small, the 64P may activate. However, it is possible
for our device to distinguish between a ground fault in a DC circuit and an AC circuit by theoperation or non-operation of this device, then early recovery can be expected when a ground
fault occurs.

Compatible with bus ducts
The AC power line between the rectifier transformer and the rectifier can be either cable or bus
duct.

Built-in backup power supply
This device maintains the ground fault detection function even if the control power supply isstopped due to a ground fault.

SpecificationsName of productAC ground-fault selective relay for rectifier (50GSR)

Equipment Configuration
Detection object
Frequency fluctuation
Constant value
Detection accuracy

Relay unit: 1 unit
Detection unit: 1 or 2 units
Cable sheath earth 3-phase lumped ground wire on the secondary side of transformer
for silicon rectifier
or bus duct grounding wire on the secondary side of transformer for silicon rectifier
Fundamental component: ±1
Third harmonic component: ±1
Ground fault current 3rd harmonic component: 5A
Ground fault current overall RMS value (entire area): OFF (not used), 20A, 50A, 100A
Operating current value: ±20% (relative to the settled value)
Return current value: 80% or less (relative to setpoint)

Operating Time

50ms or less (at 150% of setpoint input)

Relay section
Model

XGS-11

XGS-12Frequency(esp. of waveforms)

50Hz

60Hz

Detection accuracy

Display

OutputOperating current value: ±20% (relative to the settled value)
Return current value: 80% or less (relative to setpoint)
Power indicator: 1 green light
Ground fault current detection indicator: Operation indicator(orange)Ground fault current 3rd harmonic component detection
display: 1a (no-voltage contact)
Ground fault current total effective value (all areas) detection
display: 1a (no-voltage contact)

Control power supply

DC 100V/110V (fluctuation range 80V-132V)

Location of use

indoor (court, pool, etc.)

Ambient temperature

0°C to 40°C

Relative humidity

30 to 80%RH (with no condensation)

Dimensions/Mass

H237mm x W151mm x D279mm / Approx. 4.2kg

XGS-11/XGS-12

Detecting unit
ModelYGS-11

YGS-12Connector position

connector popping out

Connector under-feed

Rated primary feedthrough current

AC500A (CT ratio: 500A/1A)

Overcurrent Intensity

40x (20000A) for 1 sec.

Detection accuracy

Ground fault current 3rd harmonic component detection
display: 1a (no-voltage contact)
Ground fault current total effective value (all areas) detection
display: 1a (no-voltage contact)

Detection section pullout cable length

Maximum 50m

Display

Power indicator: 1 green light
Ground fault current detection indicator: Operation indicator(orange)

OutputGround fault current 3rd harmonic component detection: ±15
Ground fault current overall RMS value (entire area): ±15

Location of use

indoor (court, pool, etc.)

Ambient temperature-20°C to 40°C

Relative humidity

30 to 90%RH (with no condensation)

Dimensions/Mass

H134mm x W125mm x D175mm (Primary through-hole φ37mm) /Approx. 1.5kg

YGS-12