Introduction
The LV Network Calculator of Cable Pro Web software is explained in this tutorial.
In this video we show you how to design the electrical services for a commercial development. The example is based on Part 7 of the HB 301 Standard.
Project site layout explained
The site layout plan is explained as follows.
There are two buildings, the first contains five showrooms, and the second contains two light industrial units. There is a 500 kVA transformer provided by the supply authority. The transformer connects to an adjacent main switchboard, which will have an MEN link. The first building with supply connected to the metering panel contains 5 distribution boards. There is one board for each showroom. The second building, also connected to the metering panel, contains two factory units. Each factory unit has one distribution board, along with one connected downstream.
The cable lengths are shown in the diagram which will be important later for cable sizing. A protective earth cable will be reticulated with the submains cables to the buildings.
Network Settings and Supply
Under Network Settings let’s adjust the following settings:
Leave the Supply voltage, the Frequency and the Voltage tolerance values as default.
Under Allowable voltage drop since we have a substation onsite we will set the value for Network, which is the total allowable voltage drop for the installation, to 7 %. For Mains cable set this to 0.05 % since the consumers mains will be a short section of cable.
The software will automatically allocate voltage drop limits to the cables to achieve this limit. Under Cable calculation standard leave it set to the Australian Standard but there are multiple options.
Next go to the Supply from the drop down menu. We will set up the Transformer supply.
Change the Supply type to Transformer. Leave the Primary voltage as 11 kV and the Primary fault level to 14.4 kA both of which were obtained from the power authority. Switch Auto-sizing of the transformer off and enter a Custom rating of 500 kVA. Switch on Custom transformer impedance and change the Impedance voltage to 5 %.
Switchboards
Next we will add the switchboards that are downstream of the transformer and the main switchboard in the proper hierarchy. We will also set up the maximum demand for each of the switchboards. Note there are error checks inbuilt which may appear as we enter data to warn or guide us.
Add the Metering Distribution board.
Leave Phases as 3 Phase. Enter Allowable voltage drop for loads as 2 %. Leave Total load based on equal to Maximum demand calculation then this setting means all of the downstream maximum demand will be combined with that of this board.
Add Showroom 1 DB downstream of the Metering Panel. Leave Phases as 3 Phase. Enter Allowable voltage drop for loads as 2 %. Leave Total load based on equal to Maximum demand calculation then this setting means all of the downstream maximum demand will be combined with that of this board.
Go to the Maximum demand tab. Add the loads to the Showroom 1 DB. All the Showroom distribution boards have the same maximum demand. Copy 4 more switchboards for Showroom distribution boards 2 to 5 under the Metering Panel.
Add DB1 for Factory Unit 1 to be downstream from the Metering Panel and DB1-1 downstream from DB1.
For both switchboards leave Phases as 3 Phase. Enter Allowable voltage drop for loads as 2 %. Leave Total load based on equal to Maximum demand calculation then this setting means all of the downstream maximum demand will be combined with that of this board.
Both of the factory units have the same number of distribution boards with the same loads. Therefore make copies of DB1 and DB1-1 and rename them as DB2 and DB2-1. If you select DB1 and press copy it will include the downstream switchboards.
Now we have finished setting up the switchboards, their hierarchy and their demand. Let’s look at the single line diagram to check we’ve set up the switchboards correctly. Click on Single Line Diagram from the drop-down menu. Zoom with the mouse wheel and pan by pressing the mouse button to check that it matches with the installation.
