Smart RTU Controller

Finally the link between fixed hardware and software has been broken with the NGK-S pole top RTU and gas switch controller. NGK-S RTU now provides a complete solution with open architecture for both hardware and software resulting in flexibility and cost savings. This RTU lets you buy what you need now and expand later to provide more features as your needs change WITHOUT having to replace the pole top controller hardware. NGK-S RTU lets you start with simple OPEN/CLOSE control to full fault detection without removing the pole top hardware. Software changes can be done remotely without even visiting the pole top controller.

Sectionaliser Features
The sectionaliser is a self-contained device capable of automatically isolating a faulted section o­­­f line in an electrical distribution system. Sectionalisers are used in conjunction with circuit breakers or reclosers. What makes a sectionaliser different to a circuit breaker is that the isolation of the line only occurs when volts are not present. The sectionaliser will monitor the line current and voltage and use this information to open a closed switch. The sectionaliser has configurable settings for its operation Phase and earth fault detectors that are latched providing local fault history.

  1. Phase and earth fault detectors that are latched providing local fault history.
  2. One shot to lockout selector forces the controller to a single count when closing the switch for a pre-set time. If a phase or neutral current fault still exists, the controller will open the switch immediately.
  3. Live line sequence prevents the operator from closing the switch on a line that is not energized.
  4. Push button group setting selectors for current versus time presets. As an example, by programming different groups with different settings, the operator may locally select a maintenance mode of operation.
  5. Logging of fault currents at time of lockout.

Standard RTU Controller Features
The NGK-S RTU consists of an outer enclosure that is weatherproof and supplied with pole mount hardware. A single cable connects the controller with the gas switch and provides interconnection for both control of the switch, status monitoring and current measurement from the gas switch integrated current transformers. The controller operates from an inbuilt battery, external LV supply or external DC supply (e.g. solar panels). All control features are available with all forms of power supply.
The modular design is provided by six modules:

1. Power supply and backplane chassis

2. Switch interface and interlock control

3. Signal transducer and protection

4. Communications processor

5. Complex algorithm processor

6. Signal conditioner

Modules 4, 5 and 6 are optional and selected for the required level of control and monitoring. All modules may be readily replaced with the controller installed at the pole top.

Additional Exclusive Features:
Three Point Detection
Typically sectionaliser provides a single current versus time setting for detection. Additional timers are added to compensate for current transitions that may be caused by line disturbance during switching or load equalisation procedures. This tends to make the detection scheme unreliable or forces the user to extend settings so as to prevent false triggering. NGK-S sectionaliser uses three current versus time settings per phase with an additional 3 settings for neutral current. By careful selection of current and time, it is possible to reliably compensate for current transition anomalies without sacrificing performance.

Waveform Trigger Analysis in Real Time
When an upstream circuit breaker or recloser is set with a fast curve response, it is possible for downstream devices to miss voltage counts because the voltage duration is too small. The sectionaliser uses a fast waveform analyser routine that allows pickup of voltage transients with duration as little as 15ms.

Fuse Saver
When a fault occurs on a fused line with only a single fuse failing, the fault may be cleared during the reclose time and power will be restored with only two phases active. This may cause further fuses to blow or damage customer equipment. The sectionaliser incorporates a low current sensor that is triggered after an outage sequence and operates by opening the switch if the current is below a preset limit and time.

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