What is a Voltage loss calculation sheet?
Vcalc.xls is an ideal tool to pre-calculate what the Voltage drop will be in your AUTOBUS cable. In the sheet, you can enter the TDS ref’s and the cable length between all of them. You do this per AUTOBUS. If you use DOMUS you can have only one AUTOBUS. If you use PALAS, you can have up to 4 AUTOBUS networks. In that case you can make up to four different Vcalc sheets.
Download the sheet from Tools / Technical section: https://professional.teletask.be/file13
What do you get as a result
1. The total bus current consumption (to define the number of Power Supplies you will need for that AUTOBUS).
2. The Voltage you can expect at the end of the AUTOBUS cable. The sheet calculates the total Voltage drop at every interface. You need to have a minimum 9 Volt at the end of the cable.
Remark: The voltage loss is calculated as the ‘worst case’ with every interface at maximum load. Practically this never happens, except maybe at power-ON for a few seconds. So please, always respect the calculation results.
When do we recommend using this sheet
- If you are doing your first installation(s).
- If you have a pretty much loaded AUTOBUS (lots of interfaces on it with displays which are consuming more than average).
- If you have a long AUTOBUS (+100meter).
What can you do if the Voltage drop is too high
If the Voltage drop would be too high (Voltage becomes close or below 9V, this is not a problem. You will need to add one or more external Power supplies TDS10132 or TDS10134. Generally, these are installed somewhere in the middle in a distribution board. This is most of the time not the board where you have your central unit, but a sub-board on another floor or zone of a larger home/building.
How to use the Vcalc sheet
When you open the sheet, you will find four tab (below of your screen). The first tab explains how you can use the different other tabs.
Related articles
How can you know that there is a voltage drop on AUTOBUS cable
How to detect whether your Power Supply load is 70%
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