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Technical Data

Operational Features

The robust mechanical cabinet hosts an RTU controller with an integrated operator’s panel. The cabinet also contains the back up battery system required to operate the switches/ disconnectors on loss of electrical supply. NMS 100 is designed to allow remote and local operation of one to three switches, which can be extended to nine by connecting three units in series. The device is normally remotely operated but can also be controlled locally by an operator’s panel. The panel is designed to be clear and easily understood. Indications such as switch position, battery status and charging status are easily viewed. A battery test can be performed at any time to check the condition of the batteries.

Stored Energy/Battery Management

NMS 100 is provided with a rechargeable battery solution to ensure continued operational performance beyond the loss of supplied voltage.

NMS 100 cabinet temperature is thermostatically controlled to ensure battery temperatures are kept within the manufacturers’ operating tolerances. Furthermore the battery charging is temperature compensated to ensure battery health. A calibrated load further tests the batteries at configurable time intervals to ensure that their health has been maintained.

NMS 100 prevents batteries discharging beyond their minimum charge level by measuring the battery capacity at regular intervals and subsequently disconnecting the batteries from the circuit, prior to this minimum level being reached. The host system is kept informed of battery status via a number of remote status alarms, which are also displayed on the local operator’s panel.

Integrated Self-Sectionalizing Function

NMS 100 has an optional integrated self-sectionalizing function. When a line disturbance occurs a self-sectionalizing routine starts. The user can configure how the system works, by setting various timing and reclaim parameters.

The device will open within the dead-time of an upstream breaker and will close when the voltage returns for a preset period. If it closes into a fault, it will open and lockout in the next dead-time. This makes the device ideally suited for spur lines as well as to the main sections. All information is reported to the customer’s control centre for immediate real time monitoring.

Integrated Load Transfer Function

NMS 100 has an optional integrated Load Transfer function, which allows the safe switching of a customer’s HV supply from one source to another on the loss of the primary HV source. This is performed automatically and includes checking for passage of fault current to the customer side, in order to avoid unnecessary switching.

Integrated Fault Current Indicator

NMS 100 has an option to include up to two integrated fault current indicators. Depending on the current transformer arrangement these can provide either earth fault only or earth fault and overcurrent. DIP switches allow the user to configure the overcurrent and earth fault elements. The unit must see the fault current followed by a loss of HV volts before raising a remote and local alarm. A sensitive earth fault element is also included.