Track 201 – Power Planning

David Morschhauser dave@netsavvy.com

Overview

1. Power distribution basics 2. DC panel capacity planning example Add a Radar to an existing installation

3. Getting power to an NMEA 2000 backbone and equipment Single source Multiple source

Basics

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Voltage Sources

Batteries are always in a state of loosing their charge 12 Volt systems: Use 11 VDC 24 Volt systems: Use 22 VDC 32 Volt (legacy) systems: Use 20 VDC

Power supplies provide rated output – at a cost Output usually rated 5% to 10% lower

than nominal

What is the main obstacle to providing the power necessary for a component?

Wire Resistance

Ohms Law

Easy way to remember Ohms Law

Example: Cover “I” to find unknown Current

Formula is I = E/R

Example: Cover “E” to find unknown Voltage

Formula is E = IxR

Example: Cover “R” to find unknown Resistance

Formula is R = E/I

“E” is Voltage in Volts

“I” is Current in Amps

“R” is Resistance in Ohms

DC Panel Capacity Planning

Calculate existing spare capacity Load of existing equipment Feed wire gauge and length Available spare breakers or

fuses If Watts are given, convert to

Amps

Continuous vs. Intermittent Loads

Continuous Loads - Systems that run continuously while vessel is in use. These may include Panel Lighting, Navigation Lighting, VHF Radio on Transmit, Autopilot, Wipers, Depth Finder, Radar, Searchlight, Refrigerator, Engine Electronics.

Intermittent Loads - Systems that run intermittently while vessel is in use. These may include Horn, Fresh Water Pumps, Toilet, Trim Tabs, Winches.

Calculating Amperage: Step #1 Continuous Loads (12VDC)

Continuous Loads Amps Watts

P / E = I ( E=11V) I x E = P (E=11V)

GPS

Depth Sounder

Navigation Lights

VHF Radio Transmit

Total Continuous Loads

11.8 Amps 129.8 Watts

Power in Watts

Current in Amps

Voltage in volts

0.5 Amps

1.8 Amps

4 Amps

5.5 Amps

5.5 / 11=0.5A

44 / 11=4A

5.5 Watts 0.5 x 11=5.5W

44 Watts 4 x 11=44W

19.8 / 11=1.8A 19.8 Watts 1.8 x 11=19.8W 60.5 / 11=5.5A 60.5 Watts 5.5 x 11=60.5W

#1 Get the amperage rating from manufacturer documentation. Using the PIE chart below, you can calculate both Watts and Amps

SUM of Amps SUM of Watts

Calculating Amperage: Step #2 Intermittent Loads (12VDC)

Intermittent Loads

Amps Watts

P / E = I ( E=11V) I x E = P (E=11V)

Horn

Trim Tabs

Panel Lighting

Total Int. Loads

10% of total Int. Loads

Largest Int. Load (tabs)

1.54 Amps 16.94 Watts

Power in Watts

Current in Amps

Voltage in volts

3 Amps

0.4 Amps

12 Amps

33 / 11=3A

132 / 11=12A

33 Watts 3 x 11=33W

132 Watts 12 x 11=132W

4.4 / 11=0.4A 4.4 Watts 0.4 x 11=4.4W

169.4 Watts

#1 Get the Amperage rating from Manufacturer Documentation. Using the PIE chart below, you can calculate both Watts and Amps

15.4 Amps

12 Amps 132 Watts

SUM of Amps SUM of Watts

Use Greatest Value

Calculating Amperage: Step #3 Sum of Continuous & Intermittent

Loads Amps Watts

Total Continuous 11.8 Amps 129.8 Watts

Largest Intermittent

12 Amps 132 Watts

Sum of all Loads 23.8 Amps 261.8 Watts

Conclusion- Panel has 23.8 Amps of total loads

DC Panel Capacity Example

Install a radar with an existing 40 Amp, 12 VDC panel.

We know from previous slide that the panel has 23.8 Amps for existing Loads and a spare breaker position.

To find load of the radar, refer to owners manual or literature

If you know the wattage is 60W, use 11V to calculate amperage

(Amps = 60W / 11V = 5.5 Amps)

DC Panel Capacity Example Adding a Radar to an Existing 40 Amp Panel

12V DC Panel

15 Feet

15 Feet

4 Gauge Wire 14

40 Amp Main

The new radar is rated for power consumption of 60 Watts

We calculate that the radar will use 5.5 Amps at 11 V

I = P / E Amps = 60W / 11V = 5.5 Amps

We add 5.5 Amps for new radar to 23.8 Amps for existing Loads and find that the New Total Load is 29.3 Amps Total Load = Existing Load + New Load

23.8A + 5.5A = 29.3 Amps

DC Panel Capacity Example Adding a Radar to an Existing 40 Amp Panel

To New Radar

12V DC Panel

15 Feet

15 Feet

4 Gauge Wire

40 Amp Main

Panel has 4 Gauge wire 30 feet round trip distance Panel has 40A supply breaker Panel capacity is 40 Amps

Panel has space for extra breaker Panel has proper amperage capacity Radar less than 10 feet from panel Install 7.5 Amp breaker

Requirements:

3% Voltage Drop Table Refer to NMEA 0400 Appendix C5 (Chart is Conservatively Rated)

3% Drop

Current (amps)

Distance from source to device (feet) Wire gauge sizes are already computed for round trip

5 10 15 20 25 30 35 40 45 50 60 70

12 Volts

1 24 22 20 18 18 16 16 16 14 14 14 12

3 20 16 14 14 12 12 12 10 10 10 8 8 5 18 14 12 12 10 10 8 8 8 8 6 6

10 14 12 10 8 8 6 6 6 4 4 4 2 15 12 10 8 6 6 4 4 4 4 2 2 2 20 12 8 6 6 4 4 2 2 2 2 1 1 25 10 8 6 4 4 2 2 2 1 1 1/0 1/0 30 10 6 4 4 2 2 2 1 1 1/0 2/0 2/0

35 8 6 4 2 2 2 1 1 1/0 1/0 2/0 3/0 40 8 6 4 2 2 1 1 1/0 2/0 2/0 3/0 3/0 45 8 4 4 2 1 1 1/0 2/0 2/0 3/0 3/0 4/0 50 8 4 2 2 1 1/0 1/0 2/0 3/0 3/0 4/0 4/0 55 8 4 2 2 1 1/0 2/0 2/0 3/0 3/0 4/0 60 6 4 2 1 1/0 2/0 2/0 3/0 3/0 4/0 65 6 4 2 1 1/0 2/0 3/0 3/0 4/0 4/0 70 6 2 2 1 1/0 2/0 3/0 3/0 4/0 4/0

Radar

Panel

Why Derate Supply Voltage?

5 Amp @ 12 VDC

20 feet 12 Gage

About 3% or .36V

Current increases to 5.15 amp!!

NMEA 2000

Two voltage drop considerations: On the backbone itself Power distribution up to the power

insertion point

Distribute Power to Backbone

Power Distribution: Mid-Powered Backbone Example

2 LEN 6 Meters

3 LEN 4 Meters

4 LEN 1 Meter

2 LEN 2 Meters

1 LEN 6 Meters

POWER

2 Meters 6 Meters 0.5 Meters 0.5 Meters 5 Meters

Power is traveling left & right Termination Resistor

Termination Resistor

Voltage Drop Calculations: Why Do We Need Them?

Need to ensure that all devices on the network are getting adequate power Device furthest from the power

insertion point will have the largest voltage drop May not always be the last device on the

network due to drop cable lengths Additional power tees may be required Voltage drop calculations determine this

Voltage Drop Calculations: Calculating the Voltage Drop

VOLTAGE DROP CALCULATION is Ohms Law; E= I x R E = Voltage Drop (VD) I = Total Network LEN (NL) R = Backbone Length (BL) VD= 0.1 x NL x BL x Cable Resistance

– Cable Resistance Is in Ohms (Ω) per Meter – Lite Cable = .057 Ω / Meter – Mid Cable = .015 Ω / Meter – Heavy Cable = .012 Ω / Meter

Estimated Voltage Drop Calculations: Total Backbone Length & Total LEN

2 LEN 6 Meters

2 LEN 3 Meters

4 LEN 1 Meter

1 LEN 2 meters

1 LEN 4 Meters

POWER

2 Meters 2 Meters 5 Meters 3 Meters 0.5 Meters

Total BL= 12.5 Total LEN= 10

Termination Resistor

Termination Resistor

Estimated Voltage Drop Calculations: Example from previous diagram

NL (Total Network LEN) BL (Total Backbone Length) Cable Resistance-Lite VD (Voltage Drop Estimate)

10 12.5

.057 Ω per Meter 0.71 volts

E= I x R ( Ohms Law) E = voltage drop (VD) I = total network LEN (NL) R = backbone length in Meters (BL) VD= 0.1 x NL x BL x Cable Resistance VD= 0.1 x 10 x 12.5 x .057 = 0.71 volts

NMEA 2000 Backbone Power

Treat the backbone just like you would any other product Objective: deliver as much voltage to

the backbone as practical Multiple insertion points may be required Source may be battery or power supplies

Cables & Connectors: Power Tee Cables

Supplies Power to the NMEA 2000 backbone 9-16 VDC Not all Power Tees are the same Different color wires power left & right side of tee Next few slides goes over these specifics

Cables & Connectors: Power Tees

Numbers on Tee supply Power to a specific side of backbone

FEMALE Backbone Connection (some manufacturers)

FEMALE Backbone Connection (some manufacturers)

Cables & Connectors: Power Tee Wiring-Turck®

Blue : negative Brown : positive Grey : shield / drain

Black : negative White : positive

Grey : shield / drain

Data Wires pass through Tee

Must fuse at supply ends

NET-L NET-H Shield / Drain NET-C NET-S

NET-L NET-H

Shield / Drain NET-C NET-S

Cables & Connectors: Power Tee Wiring-Molex®

Data Wires pass through Tee

Black : negative White : positive Grey : shield / drain

Blue : negative Brown : positive

Grey : shield / drain

NET-L NET-H Shield / Drain NET-C NET-S

NET-L NET-H

Shield / Drain NET-C NET-S

Must fuse at supply ends

Cables & Connectors: Power Tee Wiring- Actisense®

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Data Wires pass through Tee

Red w/ stripe + Black w/ stripe - Grey : shield / drain

Red + Black -

Grey : shield / drain

NET-L NET-H Shield / Drain NET-S NET-C

Data Wires pass through Tee NET-L NET-H

Shield / Drain NET-S NET-C

Must fuse at supply ends

Cables & Connectors: Power Cable- Garmin®

Different than all others Tee is not molded Connects into a standard Tee connector 3 Amp only- Parallel Red + Black – Shield / Drain (bare)

Seldom Considered

Field attachable connector

Micro-style easily handles #14 AWG conductor

Previous examples match power pair size in Lite backbone cable (#22)

Also, can be fused to 4 amps to match Mid cable capacity

Also Undervalued (Because of $$$)

Combines redundant power supplies (or AC with a DC) Houses fuses Power indication Clamps backbone voltage

at 16 VDC

Simple Multi-segment

More segments

Shield/Drain left unconnected at all

other insertion points

Add lead to tie power supply grounds together

Questions?