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PCS-9671

Transformer Protection
Transformer Relay

PCS-9671 is a compact numerical relay for two-winding &RPSUHKHQVLYHÀH[LELOLW\LVSURYLGHGYLDWKHPRGXODUKDUGZDUH

transformers. It can be utilized for reactor or stub-bus current design, scalable function library, programmable logics,
differential protection. It also can be used to protect reactors or configurable I/Os and definable LEDs. This allows users to
implemented as a stub current differential protection in a one- create customized schemes for specific projects. Two fixed
and-a-half breaker arrangement. The restraint current differential /('V DQG  FRQILJXUDEOH FRORU /('V *UHHQ<HOORZ5HG
protection, unrestraint differential protection and restricted earth are provided. The relay is compatible with IEC 61850 station
fault protection are provided. bus and process bus applications. It supports IEC 61850-8-1
MMS, GOOSE and IEC 61850-9-2 Sampling Value. The RJ-45
faceplate port is implemented in effort to make testing, setting,
commissioning and maintenance easier.

Figure 1 PCS-9671 Functional Block Diagram

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Protection Automation Control

• Negative sequence overvoltage protection (47)

Functions Negative sequence overvoltage protection could be used to
Protection and Control detect the unbalance situation.
• Restraint current differential protection (87T)
A high-setting stage and a low-setting stage are provided • Overexcitation protection (24)
to ensure the operating speed and sensitivity. The high- Overexcitation protection is based on the ratio of voltage to
setting stage is supervised by inrush blocking and CT failure frequency (V/Hz).
blocking. In addition, the low-setting stage is supervised
by inrush blocking, CT saturation blocking, over excitation • CT circuit supervision (CTS)
blocking and CT failure blocking. CT circuit supervision consists of two elements: CT circuit
abnormality without fault detector pickup and CT circuit
• Unrestraint current differential protection (87UT) failure with fault detector pickup.
The unrestraint current differential protection instantaneously
clears serious internal faults without any restraining characteristics Management
and blocking elements.
• 1024 supervision alarm records, 1024 control operation
• Restricted earth fault protection (64REF) records and 1024 user operation records
Zero sequence differential protection is used as REF to • 64 fault and disturbance records
detect sensitive ground faults. A REF protection is provided
for each side of a transformer respectively. • 1024 SOE records

• Up to four 10Base-T/100Base-TX (RJ45) ports or two 100Base-

• Inrush current blocking by 2nd and 3rd harmonic
FX ports with IEC 61850-8-1 MMS, IEC 60870-5-103 over TCP/IP
Phase-segregated blocking, cross blocking and composited
blocking are provided upon selection. • Two RS-485 rear ports with IEC 60870-5-103

• Overexcitation blocking by 5th harmonic • Up to six 100Base-FX ports with IEC 61850-9-2 Sampling
th
Overexcitation is detected via the ratio of the 5 harmonic Value and GOOSE
current and fundamental current. • One RS-485 rear port for clock synchronization

• CT saturation detection • One RS-232 rear port for printer

CT saturation is distinguished via combined 2nd and 3rd harmonics.
• One faceplate RJ-45 port for testing and setting
• Phase overcurrent protection (50/51P) • Clock synchronization via pulse, IRIG-B and SNTP
Overcurrent protections are provided for each side of a transformer.
Inverse-time curves take into account both IEC/IEEE curves and a Auxiliary Testing Functions
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• Virtual tripping report generation and communication testing
• Zero sequence overcurrent protection (50/51G)
• Virtual self-supervision report generation and communication
Zero sequence overcurrent protections are provided for each
testing
side of a transformer. Inverse-time curves take into account
ERWK,(&,(((FXUYHVDQGDVHOIGH¿QDEOHFXUYH • Virtual binary input state change report generation and
communication testing
• Negative sequence overcurrent protection (46)
• Binary output testing
Negative sequence overcurrent protections are provided for
each side of a transformer. • Manually triggering fault recording

• Thermal protection (49)

A thermal model is adopted to continuously calculate the Features
heat capacity of a transformer. Two stages are integrated for
alarm and tripping. • This device is based on a 32-bit high performance dual-core
processor, internal high speed bus and intelligent I/O ports,
• Undervoltage and overvoltage protection (27/59) DQGWKHKDUGZDUHLVLQPRGXOHGHVLJQDQGFDQEHFRQ¿JXUHG
The voltage input can select either phase voltage or phase- ÀH[LEO\IHDWXULQJLQWHUFKDQJHDELOLW\DQGHDV\H[WHQVLRQDQG
to-phase voltage. VT failure blocking is integrated in this maintenance.
protection.
• Modularized hardware design makes this relay be easily
• Zero sequence overvoltage protection (59G) XSJUDGHGRUUHSDLUHGE\DTXDOL¿HGVHUYLFHSHUVRQ
Zero sequence voltage could be set as external voltage
injection or internal calculated voltage. • The adoption of 16-bit A/D converter and the dual-channel

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sampling technology can ensure the accuracy and reliability RIDZDYHUHFRUGLQJLVFRQ¿JXUDEOH

of protection sampling and the correctness of protection
operation. • 7KH<ĺ ǀ transfer method is used to compensate phase
angle of secondary current on each side of the transformer,
• This device can sample the analog values from the and correction coefficients are adopted to complete
traditional instrument transformers, or receive the sampled amplitude compensation.
values from the electronic transformers. It can support the
protocol IEC61850-9-2 and GOOSE. • The vector group of each side transformer is settable, and
24 vector groups available for two-winding transformer, and
• Various methods of GPS time synchronization are supported 288 vector groups available for 3-winding transformer.
in this relay, including IRIG-B, SNTP, pulse per second (PPS)
and IRIG-B synchronization. • The unrestrained instantaneous differential protection does
not be blocked by any condition so as to ensure fast tripping
• This device can communicate with a SCADA or RTU via in case of serious faults inside transformer.
different communication intermediates: Ethernet network,
RS-485 serial ports. The communication protocol of this • Three slopes biased differential protection is adopted to

Transformer Protection
device is optional: IEC61850 or IEC60870-5-103. avoid mal-operation caused by unbalance current during
external fault. At the same time, restraint capability for CT
• The human machine interface (HMI) with a small control saturation due to external faults can be improved.
module (a 240×128-dot LCD, a 9-key keypad and 20 LED
indicators) on the front panel is very friendly and convenient • The 2nd, 3rd and 5th harmonic blocking function for biased
to the user. differential protection is available. The 2nd harmonic and the
3rd harmonic are selectable to identify inrush current, and
• Complete event recording function is provided: 64 latest the 5th harmonic is used to detect overexcitation condition.
protection operation reports, 1024 latest supervision records, Besides, phase segregated blocking mode or phase crossing
1024 latest control operation records, 1024 latest user blocking mode is selectable for harmonic blocking.
operation records and 1024 latest records of time tagged
sequence of event (SOE) can be recorded. • The CT transient detection function based on the ratio of
residual current to positive current is adopted to eliminate
• The powerful fault and disturbance recording function is the influence of difference of transient characteristic and
supported: 64 latest fault or disturbance waves, the duration saturation of various CT to restricted earth fault protection.

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