DC Leakage Current Alarm System
This system constantly monitors the DC control circuits of power
plants and substations, etc., and detects ground faults on a circuit by-circuit basis.
It detects, displays, and transmits warnings for earl iest fault
recovery. It also has circuit insulation diagnosis function.

DC power supply

Voltagedivider
resistoror
Ground fault
relay (64D)Earth fault
currentig

DC Leakage
current alarmsystem

Detection of
Ground fault
circuitLeakage
Detector

Loadcurrent㏌Loadcurrent
ipMonitors load current
on each line.

Groundfault
burdenburdenEarth fault
currentig

When the constant valueof difference in load
current (ip-in) isexceeded,
it sends ground fault
alarm.

Purpose and role of system/equipment
The ground fault relay (64D) can detect ground faults on the P or N side of the DC
power supply, but it cannot detect which line is involved in a ground fault. This device
monitors the difference in load currents on each line to detect which line is involved in aground fault. This identification makes it possible to help in the early restoration of DC
control circuits.

Continuously monitors DC power supply for ground faults
The load current of the DC power supply is constantly monitored. If the difference inload current is greater than a set value (2 mA or more), it is detected as a ground fault,
and an indication and alarm are sent out.
Accident records, etc. are automatically saved to USB memory and can be viewed as
CSV files.

Insulation diagnosis function in live wire condition (leakage current check)
The insulation status of the monitored circuit (1mA or more) can be checked with theDC main circuit.

Batch monitoring of multiple circuits
One single actuator can monitor two power sources and up to 128 leakage current
circuits. (In the case of YGF-M2 type)

Equipment has self-monitoring function
It is equipped with a constant self-monitoring function to minimize maintenance.

Basic Specifications
DC power supply

ControlmethodMicrocomputer-controlled digitaltype

Detection
sensitivity

2mA (during monitoring),
1mA (during insulation diagnosis)

Alarm（1）NoticeCommunication
Test
64D(a)

ANN
Alarm(1)Resolution

Notice0.03mA

Actuator

1 to 3 seconds (when ground fault
current of 200% of set currentoccurs)

ResponsespeedCT

Test

CT

Relay terminal
blockCT

Power
Transformer

AC100V

Detector2

CTCT

64D(a)

Power
Transformer

Test
AC100VCT

Power
Transformer

AC100V

Detector3
Detector4

System configuration (YGF-M2 type)Specifications : YGF-M2 type(for large-scale (multi-circuit) facilities)*Max. 128 circuits

Name of device

Model

Dimensions
W x H x D (mm)

Mass(kg)

Actuator

YGF-M2TB-1

440 x 290 x 249.5

15.9

Detector

YGF-M2K-1

440 x 320 x 290

16.9

Relay terminal
block

TBG-1

240 x 140 x 67

1.0

ATP-1

92 x 85 x 128

2.0

ATP-2

140 x 100 x 157

6.0

YGF-M2TB-1

YGF-M2K-1

Specifications : YGF-M3 type(for small-scale (small circuit) facilities) *Max. 16 circuits
Name of device

ModelDimensions
W x H x D (mm)

Mass (kg)DC current
leakage alarmsystem

YGF-M3TB-1

440 x 290 x 378

22.8

ATP-1

92 x 85 x 128

2.0

ATP-2

140 x 100 x 157

6.0

PowerTransformer

YGF-M3TB-1

Specifications: Leakage current detector
ModelRatedvalueDimensions
W x H x D (mm)ThroughholeMass(kg)CTG-1S

DC 30A50 x 66.5 x 75

Φ15mm

0.3

CTG-2S

DC 100A

66 x 83.5 x 77

Φ27mm

0.5

CT-6F

DC 300A

145 x 180 x 180

Φ50mm

5.2

CT-6B

DC 600A

145 x 180 x 500※6×35mm28.9※through-hole bare copper strip

CTCT

V0

Switchboard-mounted type

PowerTransformer

Detector1

Alarm（1）NoticeControl
power
AC100 to 120V 50/60Hz
supplyOperating
0 to 40°C
temperature

Structure

Relay terminal
block

Alarm(2)CTG-1S

CT-6F