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MV Switchgear

HV Power represents quality Siemens MV switchgear in New Zealand . Our team has experienced project management staff, commissioning engineers, protection engineers and factory trained staff to ensure our customers get the best solution.

Vacuum Interrupter

Many of these Siemens products are based upon their “vacuum interrupter”, a technology available from, and continuously developed by, Siemens for some 30 years. Siemens vacuum interrupters use chrome-copper contact material, which minimises chopping current and thereby keeps overvoltage to a minimum. In some designs radial magnetic field contacts are used to force high current (>10 kA) arcs to rotate rapidly around the contact surfaces to reduce contact erosion, and in others axial magnetic field contacts are used, which force the arc to remain diffused, thus preventing excess contact erosion.

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Three Fusesaver aspects are highly noteworthy:

  • Three models, to suit different load currents. Yes, Fusesaver can be used on very lightly loaded lines; the most sensitive unit requires just 0.15 A of load current to ‘self-power’.
  • Ganged operation. Adding the retrofittable communication module allows three Fusesavers to act together, providing three phase tripping.
  • Options for onsite download of performance data, or remote monitoring (and control!)

Fitting the Communication Module temporarily allows:

  • A change in settings to be uploaded to the Fusesaver
  • The performance data stored in the Fusesaver to be downloaded (event data, load profile data and reliability data)
  • The Fusesaver to be open/closed by hot-stick using the red/green buttons, or operated remotely via a laptop

Fitting the Communication Module permanently allows:

  • All of the above
  • Three Fusesaver’s operating in ganged mode, communicating to each other to provide simultaneous three phase trip and close
  • Permanent communications to a pole-mounted Remote Control that connects to your SCADA via your selected communication interface. The Remote Control provides field staff local indication and control via push button
  • The Communication Module must be fitted to Fusesaver operating in the O-C-O mode (fuse eliminator)

More information on Fusesaver (Siemens web page)


8DJH Ring Main Units; 11/22 kV 630 A, indoor/outdoor

8DJH Ring Main Unit

This compact switchgear offers a wide variety of modular choices. Designs can include, ring switches, transformer feeders using fuses or circuit breakers, cable feeders, bus sectionalisers and revenue metering panels. Your specific needs can be accommodated by specifying the modules and arrangement required.

Front panel locking is intuitive and fool proof – meeting the specific needs of the NZ distribution companies’ standard practices.

The Ring Main Unit is Siemens “8DJH” series of switchgear, which features low pressure, sealed-for-life tanks, to eliminate the need for maintenance and gas handling. The 8DJH can be specified with combined or separate tanks per panel and extensible capability where bus extension and addition of further modules may be needed in the future.

Further options are available for the 8DJH series including motorised operation of disconnectors and spring recharge, auxiliary switches for remote indication, surge protection, VT & CT options and a range of protection, indication and fault passage indicators.

Bosecker outdoor enclosure for RMU

The 8DJH series of Ring Main Units are also available with a variety of enclosures to enable the units to be used in outdoor applications.

We supply three types of Type Tested enclosures for use with Siemens 8DJH series Ring Main Unit:

  • Class A [IAC A (authorised personnel) Front, Lateral and Rear]
  • Class B - Boescker [IAC B (unrestricted accessibility including public) Front, Lateral and Rear]
  • Class B - Flat pad [IAC B (unrestricted accessibility including public) Front, Lateral and Rear]

The enclosures are internal arc classified to IEC 62271-202. IAC B specification is critical for all network switching assets accessible to the public – especially where switching is under taken remotely or autonomously.

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HV Power Siemens 8DJH Ring Main Unit brochure

Class B Bosecker data sheet

Class B flat pad data sheet

More information on 8DJH switchgear (Siemens web page).


8DJH-36 Ring Main Units; 33 kV 630 A, indoor/outdoor

8DJH-36 Ring Main Unit

The popular 8DJH series of 11/22 kV switchgear has a bigger brother – the 8DJH-36.

This range of switchgear is physically a slightly larger, scaled-up version of the very successful 8DJH RMU's. In terms of front panel design and operation, it’s hard to tell the difference between the two ranges, thus saving the need for further operator training. An outdoor enclosure is also available.

The 8DJH-36 is 36 kV rated (20 kA 3 sec) with a bus current rating of 630 A. The range includes:

  • Ring switches
  • Cable to bus panels
  • Transformer fused T-offs
  • Circuit breakers
  • Air insulated billing/metering panels – arc rated (with option for cable connection left, right or both)
  • Bus section
  • Ability for VT’s to be mounted in the switchgear panel – a special extra panel for VT’s is not required
  • Automation for remote control – including earth switches if desired

Suitable for indoor applications such as power distribution systems, energy supply of utilities or larger industrial sites, the 8DJH-36 range includes several predefined, lower cost, single SF6 gas block configurations. It’s also versatile with the option to allow future extensions of panels to left or right.

More information on 8DJH-36 (Siemens web page)


NXPLUS C switchboards; 11/22/33 kV 1250 A

NXPlus C switchboard

The NXPLUS C range supports voltages of 11, 22 and now 33 kV.

For 11 and 22 kV applications the busbar can be rated at up to 2500 A. Circuit breakers of 450 mm width support 630 and 800 A circuits, and 600 mm width breakers support 1000 and 1250 A circuits.

For 33 kV applications the busbar is rated for 1250 A. 600 mm width circuit breaker panels are required and are available with 630, 800, 1000 and 1250 A rating. The NXPLUS C series is fixed pattern - that is, circuit breakers are nonwithdraw, and are also gas-insulated. This provides a very compact solution that does not require
extensive maintenance or monitoring. No gas handling equipment is required!

More information on NXPLUS C (Siemens web page)


8DA10 Primary switchboards; 11/22/33 kV up to 5000 A

8DA10 switchboard

The 8DA10 primary switchgear features single-pole metal-enclosed bus work. The 8DA10 has been available for many years and its proven field reliability has seen continued demand for this product design. The singlepole bus work reduces the likelihood of phase-to-phase faults – where at the intended primary location would have significant energy.

The 8DB10 version provides a double bus solution if that is required.

More information on 8DA10 (Siemens web page)


3AF Outdoor Circuit Breakers; 11/22/33 kV 2000 A

3AF Outdoor Circuit Breaker

Siemens Outdoor Vacuum Circuit Breakers are specifically designed to have a minimum of moving parts and a simple design in order to guarantee a long electrical and mechanical service life. The 3AG & 3AF series of live-tank circuit-breakers, use Siemens vacuum interrupters, but housed inside a porcelain pole column.

The 3AF0 and 3AG0 are restrike-free and offer reliable operation through their stored-energy spring operating mechanism. They are easy to install, operate, and maintain. Due to their modular structure and lightweight components, these Siemens live-tank circuit-breakers can easily be transported to their installation site. They can be optimally adapted to each application using current and voltage transformers mounted on the CB stand.

More info on 3AF


3AD3 Reclosers; 11/22/33 kV 630 A

3AD Vacuum recloser

Single and three pole outdoor reclosers with voltage ratings for 11 kV, 22 kV and 33 kV distribution systems are available from HV Power. The vacuum-only devices provide high performance and long life.

The Recloser head unit is electromechanical, containing no electronic devices. This eliminates the need for pole top replacements in later service due to failed electronics.

The controller is based on the Siemens (Reyrolle) ARGUS-M 7SR224 directional overcurrent protection relay, but with added features to suit the specific needs of protecting long rural lines such as differentiation of low-fault currents to overload situations, and thermal protection of lines. Although highly reliable, the controller is field removable, allowing line staff to hot-swap out the device if required, such as to apply new settings, without the need to have technical staff at site.

More info on 3AD3


3AD7 Compact Module Recloser; 27 kV 630 A

3AD7 Compact Module Recloser

By eliminating regular maintenance and utilising line voltage as power supply, the new modular auto-recloser addresses common problems of obsolete hydraulic reclosers. The compact recloser is fully rated for voltage systems up to 27kV and features a complete insulated housing that covers all live parts. The lightweight device permits easy installation and fast commissioning, plus the ability for wireless firmware and configuration updates.

The new auto-recloser is suitable for all sites, even those with inconsistent or no line current. Featuring fully configurable protection and four operations in a sequence, the unit presents the ideal solution for sectioning faults on long rural distribution lines. The system design facilitates an uninterrupted operation for most efficient service. Unlike hydraulic reclosers, the auto-recloser has no need of periodic inspection and maintenance.

More info on 3AD7


JFR Outdoor Step Voltage Line Regulators

Outdoor Line Regulators

As far back as 1933 Siemens, through its predecessor – Allis Chalmers – originated the 5-8% step voltage regulator. Today Siemens has the largest population of installed voltage regulators in the United States and worldwide.

While the range includes JFR single phase regulators, Siemens also produce the SFR three phase ground mounted regulators, which are used by several New Zealand lines companies where single phase regulators are unsuitable.

More info on JFR single phase regulators


Switchboard Components

Vacuum circuit breakers/contactors

MV devices

A range of vacuum circuit breakers are available from Siemens for your own special requirements such as new or retrofit of industrial panels, motor controls, filters and furnaces. See also here.


Instrument Transformers

Instrument Transformers

Instrument transformers are a prerequisite for measuring high voltages or currents. Their task is to transform them into small current or voltage values for measurement or protection purposes. Instrumentation transformers can be equipped with several secondary windings with magnetically separated cores of the same or different characteristics, e.g., for measuring and protection purposes. Single-pole insulated voltage transformers can be provided with an additional winding for earth-fault detection.

More info on Instrument Transformers


Guide to Siemens Part Numbers

3AD3   Pole Top Vacuum Recloser 11, 22 & 33 kV
3AD7  Compact Module Recloser
3AD8  Fusesaver
3AF   22-33 kV Outdoor Circuit Breakers
3AG   11 kV Outdoor Circuit Breakers
8DA10   Primary switchboard 11 - 33 kV up to 5000 A
8DJH   Indoor and outdoor Ring Main Units 11 - 22 kV, 630 A
8DJH-36   Indoor and outdoor Ring Main Units 33 kV, 630 A
NXPLUS C Primary Switchboards 11 - 33 kV, 1250 A
JFR & SFR  Line Regulators (Distribution Voltage Regulators)