Brief Overview of DC Systems in Transmission Substations
Transmission substations usually require 108VDC nominal battery chargers, (commonly known as 110VDC chargers due to the former use of Ni-Cd batteries) to backup and protect their switching, communications and critical loads. Fully redundant (1+1) systems are usually required in transmission substations which have a double protection system or remote back-up protection system.
It is important to mention that battery chargers and batteries associated with each protection system in the substation must be electrically isolated so that potential problems with one system do not affect the other.
There are critical and non-critical DC loads in transmission substations such as protection relays, lockout relays, SCADA equipment, breakers trip coils, security, radio and fire protection systems that can be standardized at a single voltage (108V). Usually, there is also a requirement for 24V and/or 48V for communication and other ancillary equipment. The designer will have to determine the best method to supply the various voltages.
Helios’ Experience Designing & Manufacturing DC Power Systems
More than 35 years of experience getting to know the needs of our customers allows us to understand power problems better than other providers, and to quickly design/deliver solutions specifically tailored to solve your engineering challenges. Our product range includes over 500 standard products and more than 2000 custom-made designs, including Inverter Charger Systems, Battery Charger for Industrial Applications, Battery racks, and customised form factor designs to easily fit into existing installations.
We design, integrate and manufacture in New Zealand and Australia, which allows us to have control over the entire process from the development to the final product. This enables us to reduce development cost, provide better lead times along with complete post-sales support, repair and maintenance services.
Helios’ DC systems can be customised to suit any application with options including: IP-rated and portable solutions, labelling, special terminations/connections, remote monitoring and control, N+X redundancy level, mounting and form factor, status signals and control, voltage adjustment (knob/pot), special input and multioutput options, and conformal coating.
Dual Output, Wall Mounted, Fully Controllable and Monitorable Modular Battery Charger System for Transmission Substations
Our customer required two redundant wall-mounted battery chargers 110V 5kW and 24V 1kW respectively, for powering the critical and non critical loads in a new transmission substation in the far north of New Zealand. Each one with full N+N redundancy on the battery banks for each voltage. Space restrictions were advised. The end user was currently using switch mode and modular battery charger technology.
High-temperature operation was also required, so power conversion equipment as well as batteries must meet this specific spec.
2X21U 5.5kW 110VDC & 1.2kW 24VDC Battery Charger Systems + Battery Banks
Key design features were advised and wall mounting required, our design engineers faced some challenges due to weight of equipment and heat dissipation but at the end came up with the following proposal:
- 2 X CAB 907 5.5kW 110VDC and 1.2kW 24VDC modular, redundant, compact, fully controllable battery chargers were fit in 21U wall mounted cabinet
- 4 x CSB 409 24V Diode Rack with 1XP95 diodes, ensures the load output is configured for redundant application, there are 2 in each CAB 907
- 2 X BR154 Battery Rack 3 tier for 18 X NSB210FT HT RED 210Ah – High Temperature Battery. (110VDC Chargers)
- 2 X BR155 Battery Rack 3 tier for 2 X NSB210FT HT RED 210Ah – High Temperature Battery. (24VDC Chargers)
CAB 907 Main Technical Features
- 400VAC Input for each charger
- Expandable – the power rating of each charger can be increased by adding rectifier modules
- Each out voltage is adjusted by the temperature compensation feature of the unit
- Extractor –fan power independably from external 230VAC
- Chargers configured for redundancy with output diodes
- Mains, battery and load MCBs are front access and monitored by the controller
- Various alarms per charger
- Remote monitoring and programming with a webpage interface
- SNMP v2.5 via Ethernet & Modbus
- Email Reporting
Battery Racks & Batteries
Four external battery racks with high temperature batteries NSB210FT HT RED were supplied to back up the complete 24V and 110V protection and communications system. Each battery rack has its battery test & battery terminals and fuses.
Environment is key when selecting batteries which will supply the backup power in case loss of AC of mains supply. Temperature operation, vibration and design life are some of the factors that might affect the operative life of the complete DC System.
The NSB210 HT RED 12V 210Ah High-temperature, front terminal, was the battery chosen to provide 400Ah and 200Ah to each battery bank. A key factor for choosing this battery, was the long design life at the expected peak temperature, 14 years at 30°C .