Electrical Systems
Electrical Systems
HV & MV System
The National Energy Grid of a country transports High Voltage Electricity. You will often see this as per the image below.
The HV goes to local substations. High voltage substations are points in the power system where power can be pooled from generating sources, distributed and transformed, and delivered to the load points. Substations are interconnected with each other, so that the power system becomes a meshed network.
From here the cables go to the project where it will be connected (terminated) to the projects very own substation. From this connection the project owns the power distribution infrastructure. Everything inside the Green box is a part of the national grid. Everything in the red box is owned by the customer.
The cable inside the substation will be a red MV cable. The cable will be pulled from here and connected to one side of the transformer (TX). The cable that comes out the other side of the transformer will be a black LV cable.
LV Systems
Low voltage will be the mains supply from the Substations transformers to the LV Switchroom. There will be MV cable coming from the substation to the transformer.
Then the transformer reduces the voltage and the cable coming off the transformer is now low voltage.
Single Phase LV Cable.
- Green/Yellow = Earth Cable
- Brown = Live cable
- Blue = Neutral
3 Phase Colours
TERMINATIONS
When the cable is connected to a panel or a piece of equipment it is called a termination. Below is a link to a youtube video which should explain the steps.
- Step 1 – Ensure cable is de-energised
- Step 2 – Remove the protective casing
- Step 3 – Put on the first section of the gland
- Step 4 – Pull the cable through the opening in the panel
- Step 5 – Put on the 2nd section of the gland and tighten.
- Step 6 – Put on the plastic shroud
- Step 7 – Put on the lug & crimp it
- Step 8 – Connect the lug to the panel busbar
How to Make off a SWA Gland | Steel Wire Armoured Cable Install - YouTube
NOTE: At present we are unable to track cable pulling and terminations with the Atom. We are looking at how this can be accomplished.
Busbar or Busduct
In electric power distribution, a bus duct (also called busway) is a sheet metal duct or also cast resin insulated containing either copper or aluminium busbars for the purpose of conducting a substantial current of electricity. It is an alternative means of conducting electricity to power cables or cable bus.
Typical of what you would see in an Electrical room (also called a switch room or eWall)
Typical busbar of what you would see in a Data Hall.
This busbar would run down the middle of the Data Hall to a “tap off box” where cables would run out to the servers.
UPS Systems (Uninterrupted Power Supply)
On any large scale project there will be some form of back up power. So if there was an unexpected power outage the back up will turn on in milliseconds so you will not lose power to critical systems.
Sometimes this is called “Strings” and you will have an A and a B string. Essentially if the A string breaks the B will kick in. Emergency lighting systems will also have a UPS. This will either be from a Battery pack built into the light fitting or else a separate cabling circuit which goes back to a stack of batteries (Central Battery System, CBS).
Containment
Containment is the vessel that electrical cable travels on/through. There are many types -
Ladder Rack
Used for heavy duty cables such as MV & LV/earthing.
Tray
Used for lighter cables. Often BMS controls, Fire Alarm, Security.
Basket
Used for lighter cables. Often BMS controls, Fire Alarm, Security, IT Network cables.
Conduit
Used to bring smaller cable from the main tray/basket to its final location.
Small Power
Small power is the name given to the electrical system associated with sockets that you can plug 110v equipment into.
This system will be required for the following areas –
- Administration/Reception
- Offices
- Maintenance Facilities
- Data Halls
- Plant Rooms
Fire Detection
Fire detection can be done by a number of different means.
- - Smoke Detectors
- - Heat Sensors
- - Vesda System
Your typical fire detection is a smoke detector. This is cabled back to a Fire Alarm panel. Most system operate on a double knock system. This means that smoke/heat needs to be detected in two sensers before the fire alarm/sprinkler system activates. This is the ensure a faulty reading doesn’t cause the sprinklers to go off.
Once the Fire Alarm panel gets notification of at least two smoke heads it will send a command through the BMS network to shut down the AHU’s and to close the MFSD’s (Motorised Fire Smoke Dampers). The sprinkler system normally works on a heat sensor system.
Access Control
The 8 layers of security your data center must have
1 - Perimeter security
On the outer perimeter of the data center is the multi-faceted wall, the first line of defence to withstand every possible type of attack and natural disaster. In 2017, five suspects were arrested after breaking into a data center in Johannesburg and stealing more than USD $130,000 worth of copper cables. Physical barriers are important as they serve to dishearten potential intruders. To ensure security at a maximum level, the perimeter wall needs to be coupled with additional features that we have highlighted below.
2 - Perimeter guardhouse
The second layer is the guardhouse at the fence. All visitors should be required to register at least 48 hours before their visit and answer a series of security questions from the Access Request Application System regarding their background, purpose of visit and list of accompanying people. They should only be allowed access to the facility in limited zone areas after prior screening and approval.
3 - Building entry
Upon entry, any items that visitors carry must be declared through an industrial x-ray and metal detector to ensure no unauthorized items are brought into the site.
4 - Personal access to secure zone
Visitors to the data center should then be given access passes to specify which areas they are allowed to enter, and which areas are prohibited. Then, the visitor should pass through a small air locked room – the human trap – where they get weighed, and any large discrepancies in the visitors’ weight at the site of arrival and departure will be highlighted to security to uncover the root cause. This ensures that no item gets left behind that could potentially cripple the security of the facility
5 - Lift access control
For high rise data center buildings, visitors can move from the airlock through to the liftaccess control and should only be permitted to use their designated lifts. Visitors will only be given access to certain floors to prevent unauthorised personnel. Every person with access to the facility has the potential to undermine any of the security systems, hence limiting the movement of visitors around the facility is crucial to keeping the integrity of the data center.
6 - Data hall secure corridor
Smart sensors and CCTV should be installed along the aisle to prohibit tailgating. A no tailgating policy is essential to enable the Network Operations Centre (NOC) to monitor every individual entering the data hall and beyond. This is crucial, as it ensures the accuracy of all visitor data, which would be required in the event of a security breach at the facility.
7 - Data center vault
Vaults should be under comprehensive CCTV surveillance for any suspicious activity, and to maintain visual contact of every visitor at all times, as this is where the racks are housed. At any point in time, a data center must know exactly who is in the vault, where they are and what they are doing. If there are more people than there should be, an alert that should go off.
8 - Rack level access
Only a very specific, pre-assessed, pre-approved selection of people will be given a biometric key to obtain access to the rack. As biometric access cannot be duplicated or physically stolen, it ensures the safety of the data housed on the racks. On top of this, many customers can opt to have their own rack surveillance based on their specific needs.
Commissioning
Commissioning is the process of testing all of the system in a project. Each system be it Fire Alarm, Sprinkler, Ventilation, Chilled Pipework all needs to be tested both individually and collectively.
A common way to track commissioning is by the tagging system.
Red Tag 🟥 [Level 1]
The red tag is placed on each piece of equipment completed and passed level 1 factory testing and QA QC checks.
This indicates that the equipment meets the required standards and has been approved for installation and integration into the data center’s infrastructure.
Yellow Tag 🟨 [Level 2]
At level 2, the yellow tag is used to signify the completion of component delivery, installation, and pre-startup activities.
Once all Level 2 works are completed with the tag in place, Level 3 works can commence.
Green Tag 🟩 [Level 3]
The green tag represents level 3 commissioning. The data center enters the pre-commissioning and pre-functional energization and systems startup phase at this stage.
The green tag signifies that all the components and systems are successfully checked, energized, and started up, ready for further testing and validation at Level 4.
Blue Tag 🟦 [Level 4]
The blue tag is attached after the Level 4 functional testing works have been completed on the equipment and associated systems.
During this phase, various systems and equipment are subjected to rigorous testing scenarios to assess their performance, functionality, and compatibility within the data center environment before the Level 5 works commence.
White Tag ⬜ [Level 5]
After completing the Integrated Systems Testing, a white tag will be installed on the equipment. This is the final functional testing stage integrating all systems as one, before moving to the handover/turnover stage of the process.