Impellers
- Thread starter seadaddler
- Start date
Response (little long & involved)
Aqualarm has a flow sensors just for gensets, called "save my generator", aptly enough.
Now, the question.,.
How do you automatically shut it down automatically?
Well, I, like yourself have the FP 12 mini.
Hunter installed a really nice Fireboy automated Fire extinguisher system in the boat which shuts down both the engine & the genset if the extinguisher sets off.
This is controlled by the Fireboy control box in the transom.
To shut down the engine, Hunter had FP put in a custom shut down link, that when opened, stops the genset
So, this is a NC electrical on the Seafire control box which opens if the Fireboy triggers.
But, there was a problem..
There was too much resistance in the wiring between the Seafire control box, and the FP, so the FP kept tripping thinking the Seafire went off.
What Hunter did to fix this problem was install one of their little black 12v 30A automotive relays right at the FP.
The coil was then controlled by the Seafire
So, they wired the contacts of the relay to the FP Seafire loop sense input.
You can find this mod in the online Hunter schematics.
So,,,,,
What I did was simply add a second relay which is controlled by the Aqualarm sensor. This second relay will wire in series with the FP Seafire loop as well.
But...
Now it gets tricky.
The thing is you want this circuit armed and ready to go. You need understand the nature of the Aqualarm sensors, is they have 2 states; open & closed.
In their simplist form, they are meant to only control an alarm. This is very similar to an oil pressure alarm on your engine.
The sensor is wired to the key switch, and then to a light.
The sensor is NC. When you turn on the key, the oil light comes on briefly until oil pressure is up.
This sensor is also NC. But, unlike an engine you don't have a key switch.
And also owing to something called "circular logic", you can't arm the shutdown circuit until the generstor is actually up an running. If you tried to do this, the generstor would never turn on. It would be seeing a sensor fault (no water flow) as you were trying to start it, and it would never start.
so,,,,,,
Essentially what you need is a way to arm the alarm, but only after the generator is running.
There are 2 ways to do this:
But a small 220VAC relay. This will only be a couple of bucks on ebay.
The smallest one they have is fine.
Then, wire the coil the the generstor voltage output.
So, only when the contacts close do you have a valid sensor armed output to deal with. There are a few easy places to get access to the generstor output.
Make sure to fuse the relay with a 1 Amp fuse.
Here is how I did it.
If you look on the control panel at the nav station, there is switch which says Generator & Shore, with 2 little leds.
This switch controls the big 50 Amp control relays in the AC breaker box.
Well, the 2 little LED s actually confirm that you are getting 220v either from shore or the genset. They are not just lights that come on cause the switch was rocked.
These leds are 12v.
So, I connected the generstor led to the coil of a small 12v relay.
Now, the contacts of that relay are my arming control for the generstor water intake sensor, which will only be active once the generstor is running and up to full voltage.
Hope this helps
First, the easy answer.
Aqualarm has a flow sensors just for gensets, called "save my generator", aptly enough.
Now, the question.,.
How do you automatically shut it down automatically?
Well, I, like yourself have the FP 12 mini.
Hunter installed a really nice Fireboy automated Fire extinguisher system in the boat which shuts down both the engine & the genset if the extinguisher sets off.
This is controlled by the Fireboy control box in the transom.
To shut down the engine, Hunter had FP put in a custom shut down link, that when opened, stops the genset
So, this is a NC electrical on the Seafire control box which opens if the Fireboy triggers.
But, there was a problem..
There was too much resistance in the wiring between the Seafire control box, and the FP, so the FP kept tripping thinking the Seafire went off.
What Hunter did to fix this problem was install one of their little black 12v 30A automotive relays right at the FP.
The coil was then controlled by the Seafire
So, they wired the contacts of the relay to the FP Seafire loop sense input.
You can find this mod in the online Hunter schematics.
So,,,,,
What I did was simply add a second relay which is controlled by the Aqualarm sensor. This second relay will wire in series with the FP Seafire loop as well.
But...
Now it gets tricky.
The thing is you want this circuit armed and ready to go. You need understand the nature of the Aqualarm sensors, is they have 2 states; open & closed.
In their simplist form, they are meant to only control an alarm. This is very similar to an oil pressure alarm on your engine.
The sensor is wired to the key switch, and then to a light.
The sensor is NC. When you turn on the key, the oil light comes on briefly until oil pressure is up.
This sensor is also NC. But, unlike an engine you don't have a key switch.
And also owing to something called "circular logic", you can't arm the shutdown circuit until the generstor is actually up an running. If you tried to do this, the generstor would never turn on. It would be seeing a sensor fault (no water flow) as you were trying to start it, and it would never start.
so,,,,,,
Essentially what you need is a way to arm the alarm, but only after the generator is running.
There are 2 ways to do this:
But a small 220VAC relay. This will only be a couple of bucks on ebay.
The smallest one they have is fine.
Then, wire the coil the the generstor voltage output.
So, only when the contacts close do you have a valid sensor armed output to deal with. There are a few easy places to get access to the generstor output.
Make sure to fuse the relay with a 1 Amp fuse.
Here is how I did it.
If you look on the control panel at the nav station, there is switch which says Generator & Shore, with 2 little leds.
This switch controls the big 50 Amp control relays in the AC breaker box.
Well, the 2 little LED s actually confirm that you are getting 220v either from shore or the genset. They are not just lights that come on cause the switch was rocked.
These leds are 12v.
So, I connected the generstor led to the coil of a small 12v relay.
Now, the contacts of that relay are my arming control for the generstor water intake sensor, which will only be active once the generstor is running and up to full voltage.
Hope this helps