Re: Water maker power draw

amelliahona <no_reply@...>

--- In, "edmund_steele" <edmundsteele@...> wrote:
Ed and others:
I had similar trouble with my 160 l/hr watermater on SM # 335. This behavior
began about 6 months after it was new (about the time we set off across the Atlantic).
The 20 amp breaker would trip intermittently and periodically just as yours did.

This problem continued intermittently until recently when it became more
frequent. So I checked the current draw at the 220 volt breaker panel
in the galley by using a clamp type AC ammeter and with the high pressure
pump running under load. The draw was only 13.5 amps. The breaker is a
20 amp breaker. Normally inductive motor start up loads are high and
you would expect the trip to occur with HP pump motor start, but this has
not been my experience. The trip would happen seemingly randomly and
unrelated to load or start. I didn't have a replacement breaker so I adjusted
the existing breaker. This is done by turning the red painted "set" screw on
the back of the breaker slightly. I turned mine each 1/8th turn. This tensions
a spring inside the breaker and raises the tension that must be developed on
the bi-metallic conductive strip in the breaker that causes a trip when load
exceeds the "breaker size" limit. Of course I no longer know what the actual
trip value of this breaker is. I intend to replace it with a 25 amp breaker as
soon as possible.

Note that 13.5 amps is probably not the total current draw for the desalinator.
The circuit box on the back of the watermaker control panel has a 25 amp
breaker labeled "HP" presumably for the HP pump, and also a 6 amp breaker
labeled "BP" which I presume is the "Brine Pump" or low pressure feed pump.
I will take some more measurements next time I am on the boat to verify this.
I am trying to get a copy of the schematic and logic diagrams for the water
maker from Dessalator. So far they have only offered to supplly an
installation wiring diagram. I am prepared to reverse engineer this system
to get to the bottom of these questions.

Regards, Gary Silver s/v Liahona

I had a problem with the 160 l / hour watermaker on SM#331 which
tripped the breaker when it was first put into service. There had
been a seal failure problem with the pre-feed pump and I replaced
this with no change in the breaker tripping behavior. Sometimes the
unit would operate for 30 minutes or so before the breaker tripped. I
tried simply replacing the Amel supplied 20 ampere breaker, assuming
that it was faulty but the problem persisted. After several e-mails
to Amel, they agreed that I should replace the breaker with one rated
for 25 amperes. I did this and the unit has operated perfectly for
the past 12 months. I have since discovered that at least one other
Super Maramu owner has had to make the same modification. I have
assumed that the unit must be drawing around 22 amperes in normal
operation – around 4.8 kW but I have not metered this.

Ed Steele
#331 `DoodleBug'

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