- Id
- 3
- Title
- Passive Insulation, Current and Voltage Monitoring System
- Description
- This lot will include:
Design, supply, integration, testing and commissioning of the passive insulation monitoring and associated electrical measurement equipment for incorporation within the DC Power Distribution Cabinet. The passive monitoring system shall include a resistor bridge comprising one resistor connected between positive DC and the common earth electrode and one resistor connected between negative DC and the common earth electrode. The resistors shall have nominally equal resistance values of 600 Ω and each shall be capable of continuous operation at 600 VDC across its terminals and dissipation of 600 W. In normal operation, the nominal voltage across each resistor is expected to be approximately half the overall system voltage, with an anticipated current of approximately 0.5 A through the series arrangement.
The resistors shall establish a virtual midpoint between the positive and negative DC poles for IT-system integrity monitoring. They shall be mounted to permit safe inspection, removal and replacement, with appropriate spacing, ventilation and thermal management to dissipate the heat generated during operation. The resistor bridge shall be capable of isolation from both the positive and negative busbars, preferably through externally accessible, panel-mounted isolation switches providing a clear visual indication of isolation status.
The scope shall include a high-quality DC current transducer, using Hall-effect or equivalent technology, installed between the resistor midpoint and the common earth electrode or bonding bus. The transducer shall have a measurement range of 0 to 5 A and sufficient resolution to detect changes of 1 mA. A suitable power supply shall be provided for the active sensor, together with external connections through fused instrumentation-voltage terminals, such as banana sockets, to enable connection of external measurement equipment.
The system shall also include an internally mounted voltage transducer capable of monitoring the DC potential between the positive and negative busbars at voltages up to 1500 VDC and providing a ±10 V external output. This may comprise a Verivolt IsoBlock V-1c or an equivalent product, together with a suitable power supply, protection arrangements, monitoring points and external instrumentation connections.
The IT earthing arrangement shall include an internal earth or bonding bar connected to the midpoint of the resistor bridge. The resistor midpoint shall connect at one end of this bar, with all other bonded connections positioned on one side of that point, allowing the associated insulation-monitoring current transducer to be located between the resistor midpoint and all other bonded elements. The system shall also provide an external earth or bonding point suitable for the equipotential bonding of multiple connected power devices through bolted-lug connections. The scope shall include all necessary equipment, wiring, protection, isolation, thermal calculations, functional testing, calibration where applicable, test certification, warranties, operating instructions and maintenance documentation. Additional information: Please note that the proposed lot structure remains under review and may be subject to revision as the procurement approach is finalised.
- Status
- planned