Special Protection Schemes

Our electricity transmission network includes a number of special protection schemes.

Special protection schemes allow our equipment to be operated to a higher pre-event capacity limit in a secure state. They operate after an event on the power system (such as a fault) to prevent abnormal system conditions occurring, such as overload or instability. Further, special protection schemes may be used to control electricity generation, load, or other network components.

Our latest information on each special protection scheme in our network is available below. For further information or if you have questions about these, please email [email protected].

Special protection scheme outlines

Scheme name	Island	Grid Zone	Transpower region	Outage region
HEP-ROS 110kV Overload Protection Scheme	North	GZ01 Northland	Auckland	NNI
PEN Circuit Overload Protection Scheme	North	GZ02 Auckland	Auckland	NNI
PEN Reactor Bypass Scheme	North	GZ02 Auckland	Auckland	NNI
PEN Supply Transformer Overload Protection Scheme	North	GZ02 Auckland	Auckland	NNI
ARI North Runback Scheme	North	GZ03 Hamilton	Waikato	NNI
ARI South Runback Scheme	North	GZ03 Hamilton	Waikato	NNI
ARI-HTI Circuit Overload Protection Scheme	North	GZ03 Hamilton	Waikato	NNI
ARI-KIN Overload Protection Scheme	North	GZ03 Hamilton	Waikato	NNI
CBG Supply Transformer Overload Protection Scheme	North	GZ03 Hamilton	Waikato	NNI
HTI Supply Transformer Overload Protection Scheme	North	GZ03 Hamilton	Waikato	NNI
EDG-KAW 1-2 Overload Protection Scheme	North	GZ04 Edgecumbe	Bay of Plenty	NNI
EDG-OWH 2 110kV Overload Protection Scheme	North	GZ04 Edgecumbe	Bay of Plenty	NNI
KAW T13 Overload Protection Scheme	North	GZ04 Edgecumbe	Bay of Plenty	NNI
KMO Intertrip Scheme	North	GZ04 Edgecumbe	Bay of Plenty	NNI
MTI Runback Scheme	North	GZ04 Edgecumbe	Waikato	NNI
THI Generation Intertrip Scheme	North	GZ04 Edgecumbe	Central North Island	SNI
HRP Anti-Islanding Scheme	North	GZ05 Hawkes Bay	Hawkes Bay	SNI
RDF T3 T4 Transformer Protection Scheme	North	GZ05 Hawkes Bay	Hawkes Bay	SNI
TAB Anti-Islanding Scheme	North	GZ05 Hawkes Bay	Hawkes Bay	SNI
HWA Automatic Under-voltage Load Shedding Scheme	North	GZ06 Taranaki	Taranaki	SNI
BPE-MTR Circuit Overload Protection Scheme	North	GZ07 Bunnythorpe	Central North Island	SNI
BPE-WDV 1 and 2 Circuit Overload Protection Scheme	North	GZ07 Bunnythorpe	Central North Island	SNI
MTN_WGN Circuit Overload Protection Scheme	North	GZ07 Bunnythorpe	Central North Island	SNI
TKU Circuit Overload Protection Scheme	North	GZ07 Bunnythorpe	Central North Island	SNI
WGN Under-voltage Load Shedding Scheme	North	GZ07 Bunnythorpe	Taranaki	SNI
CPK Transformer Overload Protection Scheme	North	GZ08 Wellington	Wellington	SNI
MGM Overload Trip and Autochangeover scheme	North	GZ08 Wellington	Central North Island	SNI
WIL 110kv Bus Split Scheme	North	GZ08 Wellington	Wellington	SNI
BLN-KIK 110kV Circuit Overload Protection Scheme	South	GZ09 Nelson	Nelson-Marlborough	SI
KIK STK 3 Circuit Overload Protection Scheme	South	GZ09 Nelson	West Coast	SI
KIK-STK 220 kV Circuit Outage Intertrip Scheme	South	GZ09 Nelson	West Coast	SI
TIM Supply Transformer Overload Protection Scheme	South	GZ11 Canterbury	South Canterbury	SI
TIM T5 T8 Overload Protection Scheme	South	GZ11 Canterbury	South Canterbury	SI
TMK Supply Transformer Overload Protection Scheme	South	GZ11 Canterbury	South Canterbury	SI
COL Intertrip Scheme	South	GZ12 West Coast	Canterbury	SI
HOR Automatic Under-voltage Load Shedding Scheme	South	GZ12 West Coast	Canterbury	SI
AVI_BEN Circuit Overload Protection Scheme	South	GZ13 Otago	South Canterbury	SI
CML-FKN Circuit Overload Protection Scheme	South	GZ13 Otago	South Canterbury	SI
FKN Circuit & Transformer Overload Protection Scheme	South	GZ13 Otago	Otago-Southland	SI
OAM-WTK Circuit Overload Protection Schemes	South	GZ13 Otago	South Canterbury	SI
GOR Circuit Overload Protection Scheme	South	GZ14 Southland	Otago-Southland	SI
HWB T6 Reverse Power Protection Scheme	South	GZ14 Southland	Otago-Southland	SI
MAN Generation Intertrip Scheme	South	GZ14 Southland	Otago-Southland	SI
NMA Capacitor Bank Intertrip Scheme	South	GZ14 Southland	Otago-Southland	SI

Special Protection Schemes

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Special protection scheme outlines

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