MickinDallas wrote:

Can you use a automatic solenoid changover switch when switching over from
shore power to an Onan MDJA diesel genset? The instructions I have
indicate that the load must be removed first, the genset started and then
the load applied. Is there a way to do that with a solenoid operated
automatic transfer switch?

MickinDallas


If you are on shore power, start the genset, then use a switch or
solenoid (relay) to switch over. An automatic control circuit is not
a purely simple arrangement.

"Solenoid" usually refers to a relay type coil operating a single
pole single throw switch or a mechanical actuator for something
else, as opposed to a relay switching arrangement, which would
actuate a fancier switch, or set of switches. (That's a local
technical use, about which otherwise mindless 'droid electrical
engineering students would centre a beer drinking preamble to
pointless fisticuffs.)

A relay contains a coil, which is often considered a solenoid if it
operates from D.C. Stroking differently produces different folks,
and loose language sinks ships as well as swelling lips.

Shutting off the genset could cause the switchover relay to drop
back to the shore input feed so long as the power from the shore
could not conflict with the power for the relay. It would be easy to
make a mistake in the wiring which would cause such a mishap. The
two Alternating current power sources must never be connected
together, even for an instant, as the explosion would cause
complaints about blackouts, spilled drinks, clouds of smoke in the
clubhouse, etc. A manual switch could force the feed to go back to
shore power while the genset is running by controlling the operation
of the relay / solenoid. This arrangement should be OK and is
relatively simple and safe.

The genset should start up OK with only the small load of a relay
present. You may need a small delay circuit to get the genny up to
full speed before switching over. You may prefer to do this
switchover manually, as it would be much simpler. If you are doing
it manually, a simple, large DPDT switch in a box near the genny
start control should suffice, so long as you do not need
uninterruptible power for some loads such as computers. In that
case, a commercial UPS using chargers, batteries, and inverters
should handle that load while switchover occurrs. A laptop computer
already contains circuitry to enable lossless operation while
unplugging it's AC power, and plugging it back in, which is about
the same as switching the AC power distribution from one source to
the other.

Commercial automatic switchovers are available. Typical household
devices, sheltered from the weather and sea spray should be fine.

If you insist on home brewing some nonstandard automatic operation,
you need to decide and describe precisely how you want the
arrangenent to work, and how automatic you want it. You may want the
genny to start automatically whenever shore power is not present,
etc, to preserve refrigeration and power bilge pumps. There is no
end to the ingenuity of the uneducated in dreaming up unlikely,
false or fanciful requirements.

Since you had to ask, perhaps you should start with a basic
electricity course, or consult with a professional.

You have to pay properly qualified professionals, but at least, if
they make a mistake and sink you or kill you, your insurance is not
jepoardised.

Terry K

In article
outelectronicequipment
..com,
"MickinDallas" wrote:

Can you use a automatic solenoid changover switch when switching over from
shore power to an Onan MDJA diesel genset? The instructions I have
indicate that the load must be removed first, the genset started and then
the load applied. Is there a way to do that with a solenoid operated
automatic transfer switch?

MickinDallas


The bigger question is how long do you let the MDJA warm up before you
apply the load to it, and does this all happen automatically? There are
a pile of Third Party sequencers that can do the job, but I have never
seen an ONAN Labled Setup for a MDJA Genset. Most users prefer to do
the whole job manually, so they can monitor and adjust the sequence, as
required for good operating practices.

Bruce in alaska
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add a 2 before @