［ Power Source Products for Special Applications ］

Short-Circuit Generator Set for
AICHI ELECTRIC CO., LTD.
Keywords

Short-circuit generator, Static excitation system, Medium-voltage inverter

Abstract

A short-circuit generator system is used to supply heavy currents and large
power for the testing of circuit breakers, switchgears, insulators, and transformers
by driving a generator with a motor.
We recently received an order for a 330MVA (3Hz) short-circuit generator
system for the High Power Laboratory of AICHI ELECTRIC CO., LTD., and supplied the system on full-turn-key contact. Major products we supply are a
short-circuit generator system (motor and generator), reactors, medium-voltage
inverters, control panels, monitoring systems, closing switches, circuit breakers,
test sequencer, and measuring devices.

1 Preface
We supplied a short-circuit generator system
to AICHI ELECTRIC CO., LTD. Our scope of supply
includes the main part of the short-circuit generator
system and a control panel. Others include a closing switch, a test sequencer to control a closing
switch and closing phase, and measuring devices
for currents and voltages. This paper introduces theitems mainly supplied.

2 Short-Circuit Generator
2.1 Motor-Generator Set
The ratings of the short-circuit generator andthe motor to drive this generator are as speciﬁedbelow.
( 1) Synchronous generator
330/275MVA (3Hz) – 60/50Hz – 2P – 3600/3000min−1– 13200/11000V (Y)/7620/6350N (Δ)( 2 ) Induction motor
1120/933kW – 6600/5500V – 60/50Hz – 2P – 3600/
3000min−1
Fig. 1 shows an equipment layout drawing. For
the generator, a 2-pole machine has been adopted
because of its high revolving speed and large inertial
energy. For the excitation system of the generator, astatic excitation system with high responsiveness isadopted. Generator windings can be changed overbetween y-connection and Δ-connection with the24

Noriyuki Koshizuka

MEIDEN REVIEW Series No.167 2016 No.2

aid of an external disconnecting switch. For they-connection at 60Hz, the rated voltage is 13,200V.
At 50Hz, the rated voltage is 11,000V. For the Δconnection, the rated voltage is 7620V at 60Hz and6350V at 50Hz, respectively. The system capacity isdesigned to carry a short-circuit current of morethan 20kA for the Δ-connection at 60Hz.
The adopted driving motor is a squirrel-cage
rotor type induction motor. A medium-voltage inverter
system is adopted for start-up operation and speed
control. Bearings for the generator and the driving
motor are of the plain sleeve bearing type. The lubricating system provides a lubricating oil from a forced
lubricating oil supply unit at the time of start-up andstoppage. While the system is operated at the rated
revolving speed, however, a pump directly connectedwith the motor-generator shaft feeds a lubricating oil
to bearings for saving energy.

2.2 Control Unit
Fig. 2 shows the switchgears and Fig. 3 shows
the single-line connection diagram of this short-circuit
generator system.
( 1) Medium-voltage inverter
The medium-voltage inverter consists of threepanels. The basic function is speciﬁed to control thespeed at 3600min−1 at 60Hz and 3000min−1 at 50Hz.
Its main feature is that the inrush current is small at
the time of start-up. In addition, restarting is possible even in the middle of a stopping sequence.

Stairs

Waiting roomDriving
power
supplyFeederpanel 24765

Operation room

Auxiliarypanel

DCsupplyunit

Lubricating equipment

Incoming
feederpanel 1

Monitoring control desk

StairsStairsInverter panel

Closing switch
TRS

VCB for R S
protecT
tion

R
S
T

Throughbushing

Soundproofroom (Test bay)

Short-circuit generator
AVR
panel

15,235Generator room

SCR
panel

Reactor R

DS
DS

DS

RL Phase R(Existing)
RL Phase S(Existing)DS

DS

Electricity room
DS

DS
DS

Capacitors(Existing)

DS

DS・CH

Circulating
pump

Fig. 1RL Phase T(Existing)CoolerpipingStairsDSReactor SDSCH

Reactor TCHDisconnecting
switch for
y-Δ conversion

DSLow-voltage
high-current
transformer(Existing)

DSCH

Exciting
transformer

Emergency genset

11,00012,000

Unit: mmEquipment Layout Drawing

Major products are neatly organized. In so doing, we factored the reduction of the overall footprint in the generator room.

Fig. 2Switchgears

The switchgears are allocated in the line beside the short-circuit
generator.

( 2 ) AVR panel
The AVR control range is 0 to 110%. Using atouch panel mounted on the panel surface, the generator voltage can be regulated. Thyristors for rectifying ﬁeld currents have enough capacity to carry
4000A in a short time.
( 3 ) Monitoring and operation panel
Fig. 4 shows the control room where a touch
panel is installed. Using this touch panel, various
operations are possible at the monitoring and operation desk in this room, from the operation and stopof the auxiliary machines, to the run-stop of the mainmachine set and startup operation for short-circuit
testing. Since indicator lamps and graphic panels
are installed, it is possible to look over the full viewof the testing system.
MEIDEN REVIEW Series No.167 2016 No.2

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26MEIDEN REVIEW Series No.167 2016 No.2

IM

CLR

64B

51F2

AS

Single-Line Connection Diagram

EXT

Exciting
transformer

＊A

ZCT

2CT

VCB
7.2kV

A single-line connection diagram is shown.

Fig. 3

Driving motor

Wh

Feeder panel 2

A/TC

VS

＊A

A

27B

V/TD

67F2

AS

51R

＊A

ASA

CT

M

W2

CT
U2

VT

U1

R

SG

V1

S

VT

Current
limiting
reactors

Current
limiting
reactors

Current
limiting
reactors

Current
limiting
reactors

LA

GCB
36kV

LA

LA

GCB
36kV

LA

W1VT

EncoderCurrent
limiting
reactors

T3CTF1F23VT

T1

S1Bus ductconnections
Fromexcitingtransformer

A

CT

K50

V/TDN

From inverter panel

A

From Incoming/Feeder panel 1
From inverter panel

V

From Incoming/Feeder panel 1To measuring devices

R4 S4 T4

Thyristor
unit

51EX51GVT K50

K60

59G

VS

Sh

AVR

V

R

R

DV/TDDV/TD

HV SCR panel

F

V

AVR panel

From SCR panel

V

F

From SCR panel

A

T2

S2

R2

Low-voltage high-current transformer (Existing)Monitoring and operation deskR3 S3 T3

Short-circuit bars

Short-circuit bars

R1

Short-circuit bars

Short-circuit bars
Short-circuit bars

To measuring devices

Current
limiting
reactors

LAVCB
15kV

GCB
36kV

LA

275/330MVA at 3-cycle-50/60Hz
Voltage: 6.35/7.62kV (Δ connection)
11.0/13.2kV (Y connection)
Synchronous generator

CT

V2

3PLBS

Auxiliarypanel

Bus ductconnections
To HV SCRpanel

AV

Vo

Incoming/Feeder panel 1

67F1

51F1

A/TD

TR

VCB
7.2kV

EVT

933/1120kW-5.5/6.6kW-50.5/60.6Hz-120A

HCTInverter panel

Incoming
transformer
panel

ZCT2CT2CT

VCB
7.2kV

3φ-6.6kV-60Hz

Fig. 4Control RoomFig. 5The control room is shown. Various operations can be carriedout from here.

Closing
GCB

An external view of reactors is shown.

Signal converter unit
BNC
female

VCB
forprotection

BNC
femaleBNC
femaleFrom short-circuit
generator

To suppliers

BNC
female

BNC
cable

BNC
female

BNC
cable

BNC
femaleBNC
cableReactors

BNC
BNC
female female

BNC
BNC
male
male
10：1
Probe
BNC
BNC
male
male
10：1
Probe
BNC
BNC
male
male
10：1
Probe
BNC cable

BNC
BNC
female female

ShSh

LC duplex
optical fiber

Receiver unit

LC duplex
optical fiber

Receiver unit

Transmitterunit

BNC
femaleBNC
male
LC duplex
optical fiber

Receiver unit

BNC
male

BNC
male

Transmitter
unit

BNC
female

BNC
male

BNC
male

Transmitter
unit

BNC
femaleCoaxial cable

BNC
male

Transmitter
unit
Transmitter
unit

BNC
male

BNC
male

Transmitter
unit

Transmitter
unit

BNC
BNC
female female

Sh

Transmitter
unit

BNC
male

Transmitterunit
Via touch panel

Memoryhighcorder

Rack top
Electrical room

Fig. 6

Test bay

Operator console
Monitoring and control room

Measuring System Diagram

A measuring system diagram is shown. Optical ﬁber cables are adopted for insulation.

MEIDEN REVIEW Series No.167 2016 No.227

( 4 ) Others
In the event of a power outage for this testingsystem, the interruption of lubricant supply to bearings is a big concern. As such, an emergency generating system is used as a backup power for theauxiliary power supply. At the same time, a DC
pump is installed. In this manner, this makes aredundant lubrication oil supply system which isintended to improve reliability.

3 Reactors
Fig. 5 shows a view of reactors. Two reactor
sets with different capacities are allocated to eachphase. Reactor 1 is served by seven combinationsof changeover switches, and four combinations ofchangeover switches for Reactor 2. Twenty eight(28) combinations of current adjustment are, therefore, possible.

4 Closing Switch
In short-circuit testing, a closing-phase control
function is required. The supplied test sequencer
assures a high performance of adjustments to atesting condition of 1/10000s (0.1ms). Signals fromthe test sequencer are controlled through high-speed
conversion performed by the Insulated Gate Bipolar
Transistor (IGBT) switches. For the closing switch, a36kV gas-insulated circuit breaker is adopted, whichassures a closing accuracy of ±0.5ms.

5 Measuring Devices
Fig. 6 shows the measuring system diagram.
The current transformers that measure short-circuitcurrents are installed in the test bay. These are special products rated 30,000/15A. They use the BNC
connections where a 1Ω resistor generates a 15V
voltage.
Optical ﬁber cables are used between the test(bay where equipment under test is placed) and themonitoring and control room (where the measuring
devices are installed). This is an excellent measured
data transmission method because the optical ﬁber
cable can insulate the surge voltages caused by theswitching of short-circuit currents or high voltages.

6 Postscript
A short-circuit generator system is an important facility for the performance veriﬁcation of circuit
breakers and switchgears. Customers who haveshort-circuit generator systems are limited in number and regular orders cannot be expected. We
consider, however, our mission is to keep improving
technology for our customers.
Lastly, we would like to express our gratitude to
all project-related personnel for their helpful suggestions and guidance for the production and supply of this system.
・All product and company names mentioned in this paper are
the trademarks and/or service marks of their respective owners.

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