Tuesday, 18 October 2016

Shore Power Conversion & Electrical Ramblings

Lifted out of the water and propped up on the hard stand here in Trinidad, we find ourselves for the first time having to deal with 110 volt / 60 hertz AC power. Yes, we're in a USA influenced part of the world, but Crystal Blues is a 220 volt / 50 hertz vessel. It's been kind of amusing getting things sorted out, without blowing anything (or anybody) up. Most amusing is the fact that right now we have three (yes three, count 'em) separate shore power cords connected to support our quasi-camping life style here on the hard stand.

Three Different Sockets, All 60 Hz, Some 2-Phase 220v.
First, The Shore Power Supply

Our regular shore power lead is now plugged into a 30 amp 110 volt 60 hertz supply. On-board the boat, this is passes through a Mastervolt Ivet-C isolation transformer to raise the voltage to 220 volts, though it is still at 60 hertz frequency. The transformer provides voltage matching and isolates us from the marina electrical ground system.

Most of the time we can operate from this shore power supply, as (surprisingly) much of the equipment on-board is quite happy with a 60 hertz supply.  We can use our battery charger, power tools and vacuum cleaner, home appliances, hot water heater, media and computer equipment, all without problems.

Only the galley microwave, the refrigeration and the boat's central air conditioning will not run on 60 hertz. This is not a big problem right now - when we need to use the microwave we switch over to the inverter and run it off the batteries. The refrigeration and central aircon are both sea water cooled, so they cannot be run while we are out of the water anyway...

Second, Real Time Conversion

Our second connection is direct to the battery charger only.  In the long term, once we are back in the water, most of our needs in this part of the world will be met by the real time conversion process.  Shore power will go only to the Mastervolt Chargemaster 100 amp battery charger. That charger works from almost any shore supply frequency to feed the batteries up to 100 amps of (nominal) 12 volt DC power - this equals happy batteries.

At the same time, the Mastervolt Mass Sine inverter uses this DC supply to create a clean 220 volts / 50 hertz sine wave power supply (at up to 2000 watts) that will run most of the boat's systems. Once we're out of the boat yard, living afloat again, that process allows us to run even our big water cooled refrigeration compressor - the inverter starts and runs that compressor easily. In fact it will also run the central aircon, but I do feel guilty even contemplating that type of decadence at sea. Also a little embarrassed to admit that I've even tested it (which I have) ... but then again, a Tesla car runs air conditioning from a battery supply - why shouldn't we do the same ? Maybe when our batteries are bigger.

At this point we should really give thanks to Bob Wisniewski who initially opened my eyes to real time conversion and who clearly simplified our life in the 60 hertz world . Back in the year 2000, when we were refitting Crystal Blues for the first time, Bob owned and managed Power Protection Solutions in Queensland, Australia. We wanted to buy a new (single combi unit) Mastervolt Inverter/Charger from him, but Bob asked me some pertinent questions and then recommended against it.

He said that if we were staying in the Australian / Pacific / Asian region then a single unit "Combi" Inverter/Charger would be just fine. However, if we planned to cruise further afield, entering the area of 60 hertz power supply, then installing a stand alone inverter and a separate charger would serve us better - and he's right. Real Time Conversion keeps our systems running at all times, and we don't need to worry about the voltage or frequency of the shore supply. So a big thanks from us to Bob Wisniewski, whose vision is keeping our beer cold in this 60 hertz world! Note : Bob is now working with BLA in Queensland, the current Mastervolt distributor in Australia.

Third, The Air Conditioning

It is damn hot here. Power cord number three is for a rented A/C unit, provided by the boat yard, that operates on that quaint 220 volt dual phase 60 hertz system that pollutes US society.  It has no neutral conductor, so is considered kind of dangerous by us purists. It should be protected by dual pole circuit breakers at all times, but you can guess correctly that it rarely is in practice. In fact the power supply poles here do not have any circuit protection at all - no breakers, no earth leakage devices at all - yoiks. So the boat yard provides the AC unit to sit on the deck, a fiberglass housing to direct the cool air down below and the necessary 220v / 60hz cabling. That's cord number three, keeping us cool while out of the water, but definitely not plugged into the boat thank you very much.

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