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Track 201 – Power Planning
David Morschhauser [email protected]
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
+
? -
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®
+ -
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?