Practical Boat Owner - February 2016

Gear

A1

Oil

Pressure

A2

Coolant

temp

A3

Fuel

level

A4

Domestic

current

A5

Charging

current

A6

Battery

2 Volts

P1(+/-)

factor

Sense volts 1 0.1 2.7 0.01 0 0 2

011

Field value 1 0 17.5 0 0 0 1.9

Sense volts 2 1.19 0.3 1.64 0.75 3.0 14.1

Field volts 2 102 90 100 15 60 13.9

Alarm value 00 77 1 00 00 10

Current source ON ON ON OFF N/A N/A

on the display: accuracy is secondary to the fact that it would be running
‘higher than usual’. Don’t forget, you still have the alarm switch function of
the original engine electrics, and an early warning alarm value (say 85°C)
can be set in the RS11 so the chart plotter sounds off before then.

Fuel tank level sender
Hold the sender with the float at the bottom and read the voltage in
the terminal viewer, and repeat with the float at the top.

Domestic consumption and
charging current measurement
Again this is straightforward, as the current signal for both the shunt
(domestic consumption) and Hall sensor (charging), amplified by the
AD50 differential amplifiers, give an output of 50mV/A and is linear. No
current source is required.

Battery 2 voltage
No sender is required, and the set-up is simple.

Engine revs
Connect the ‘W’ terminal on the back of the alternator to the P1(+) input
and P1(-) to 0V: this isn’t normally
necessary, but without
it occasional glitches will occur
with some alternators. The
calibration is set by entering a
multiplier value in the Port RPM
box and matching the displayed
value with the rev counter. For this
engine/alternator combination,
the value is 11.
The table below shows the full
set-up. A little trial and error is
required to get the displayed
values just right. Where you have an alternative means of taking the same
measurement, a comparison can be made. The main concern, however, is
to detect a change in the normal operation of the engine due to a problem:
absolute accuracy is a secondary issue, really.

Rev counter connection on the

back of the alternator

Actisense EMU-1

Engine Monitoring Unit

Again, there are six ‘gauge input’ channels, but the main difference is

that the Actisense EMU-1 is pre-loaded with a range of sender

characteristics (including the non-linearity of temperature senders)

which makes the configuration very simple but, of course, inflexible.

You only have to choose the engine instance, then the parameter for

each channel, and select your sender from the drop-down list. The

EMU-1 then has four alarm inputs which are connected to the switch

part of the senders: only two are used in this installation. It is strongly

recommended that you retain the original engine electrics alarm

connections, but you can also connect them to the EMU-1 alarm inputs

as well if desired. Finally, there are two tacho inputs.

Channel allocation

(Instance 0 and current source ‘Auto’ for each)

G1 – Coolant temperature G2 – Oil pressure

G3 – Fuel tank level G4-G6 – Not used

A1 – Oil pressure sender low-pressure switch (set to trigger below 5V)

A2 – Temperature sender over-temperature switch (set to trigger below 5V)

A3 – A4 Not used

T1(+) – Alternator ‘W’ terminal for engine revs. (Ratio PPR = 11.5)

T1(-) – 0V

T2 (+/-) Not used

Battery volts are measured internally from the EMU-1 supply.

The EMU configuration tool is easy to use. The drop-down lists show all

the available senders for the parameter being measured

EMU configuration tool

This is very straightforward to load, although it is necessary to buy the

Actisense NGT-1 USB to use it. The communication between the config

software (on your computer) and the EMU-1 is through the NGT-1 USB into

the NMEA2000 network backbone. If you have a Raymarine (STNG)-style

backbone you will need two DeviceNet (female) to STNG cable adapters

for the NGT-1 and EMU-1. Currently, the configuration software does not

allow existing engine hours to be entered or allow the overall set-up to be

saved, so write it down as you will have to re-enter it all next time.

Engine and electrical data displayed on the chart plotter