How to calculate a voltage drop

Firstö voltage drop calculations
Searching; we have already covered the structure of your NMEA 2000 network. Now we must first the basics behind tensions on a network and how the implementation of power management must be considered. In this article we will cover stress case calculations, which explains why the basics of the previous article are different; important.

Voltage drop is essentially the amount of voltage taken by devices along the backbone, between each device and the end of the network. Voltage drop on a network is limited by available voltage, the type of power supply used and distribution loss.

We need voltage drop calculations. to ensure that all devices are getting enough power.

One thing to keep in mind with voltage drop calculations is that it is not always It is the "last" device in the network that will have the biggest voltage drop, rather it is the device furthest away from the stress point. (Drop cableänder änänänänäse).

Usually available the två types of network tools;

- Driven, where the network is built only once and is usually found at the end of the ;nster/hög side of spine.

br>

– Intermediate powered, where the power supply drives both left and right sides of the trunk node independently, and this is placed near the center of the network.

Figure 2 – Intermediate network

På large networks, however, there may be a requirement for several isolated power lines on the mains network must ensure that each unit receives sufficient power. Installation of multiple accessories should be done with care, and it is always recommended that a certified NMEA installer perform all device or power installations on your network.

If more than one current is required, it is important that the current direction is drawn out. For example, if you have 1 strömförsöröaring; the middle of the network and needs more current further down the network on right side, så the second power supply must only be connected to the right side.

Several insulated power supplies MUST be of the same make and model

Figure 3 – Multiple Power Tap installations NMEA documentation

Power supply and voltage drop calculations have a "loss budget", which is the maximum voltage drop in the mains that ä to the facility, depending on type of supply.

This is explained in the following table from NMEA:

Figure 4 – Loss budget NMEA documentation

NMEA voltage drop calculator:
Voltage drop calculations are performed using Ohm's law, where

E = I * R
E = Voltage drop
I = Total network LEN (NL)
R = backbone length (BL)
VD = 0.1 * NL * BL * Cable resistance

Cable resistance varies depending on; which cable is used, Lite, Mid or Heavy Cable;

Lite = 0.057 Ω / meter
Mean = 0.015 Ω / meter
Tung = 0.012 Ω / meter

In this example på a Lite cable network;

NL = 10
BL = 12.5

Cable resistance = 0.057

VD = 0.1 * NL * BL * Cable resistance
VD = 0.1 * 10 * 12.5 * 0.057 = 0.71 V

An important reminder: If you have a medium-powered spine, you must ask ;kings onå left and right sides are done separately.

Additional calculations
In some installations, segment voltage drop calculations are used, especially if voltage; the case exceeds the permitted limits. This is usually when the drop exceeds 1.17V from a battery and 3.61V when using a 13.8VDC mains supply.< /p>

Segment voltage calculations are done by treating each part of the backbone individually and calculating the voltage drop across each segment/drop cable and the device connected to the bus via; that place. These are done for a number of reasons, but the most common reasons are:

The initial estimated voltage drop from the normal calculations is very close to Therefore, detailed calculations are required to ensure that the network will work correctly.

• If the result of the initial estimate does not Detailed calculations are clearly required.
• If more flexibility is required with the installation, or if units need to be moved around until the voltage levels of the network learn mpliga.