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Generator Auto-Start
07-07-2017, 22:27 (This post was last modified: 07-07-2017 22:28 by cmillsap.)
Post: #1
Generator Auto-Start
We just entered The Wild Horse Hotel and Casino’s RV park this afternoon. We weren’t here for more than 2 hours when the park's power grid failed. My neighbor said it’s a daily occurrence and lasts for 1 hour to 4 hours.

I’m glad I didn’t have my Gen Auto-Start turned on as all four a/c s were running. I’m not a big fan of leaving the Generator Auto-Start function on. Here’s why;

A generator should be started with little or no amp load on it. Once started and running for a short warm up period, the load should be slowly added. The same procedure should be used when shutting down a generator. IOW, systematically lower the load before shutting down the generator.

If I have a shore power failure, my four A/C units SMX thermostats will restart all the powered-on A/Cs once the power is re-supplied by the generator. If all 4 A/C units were running before the power failure plus some other small stuff plus the inverters, the initial amp load on the generator would be extremely high.

If I have shore power failure, I would rather start the generator manually and add the loads one at a time.
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07-08-2017, 01:24 (This post was last modified: 07-08-2017 10:22 by travelite.)
Post: #2
RE: Generator Auto-Start
Chuck,

There's a start stagger on-delay programmable in the SMXII's that prevents the AC's from turning on at the same time; it's called the "Compressor Time Delay" in the attached doc. For the ACs that are powered thru the Trace SW inverters, upon blackout the inverters will seamlessly pick up the load and sync with the generator, passing the loads onto the generator after 20 or 30s. While this isn't enough time for the genny to fully warm up, at least the waveforms are in phase which takes a huge strain off the equipment, the genny waveform is stable, and in-rush currents are eliminated. Most transfer switches have a delay of 30 to 60s to allow the genny waveform to stabilize. Sometimes this delay is configurable.


Attached File(s)
.pdf  SMX_II_CONTROL_SYSTEMS_DX.pdf (Size: 493.14 KB / Downloads: 7)

david brady,
'02 Wanderlodge LXi 'Smokey' (Sold),
'04 Prevost H3 Vantare 'SpongeBob'

"there is no perfect forum there are only perfect forums"
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07-08-2017, 13:21 (This post was last modified: 07-08-2017 14:22 by cmillsap.)
Post: #3
RE: Generator Auto-Start
(07-08-2017 01:24)travelite Wrote:  Chuck,

There's a start stagger on-delay programmable in the SMXII's that prevents the AC's from turning on at the same time; it's called the "Compressor Time Delay" in the attached doc. For the ACs that are powered thru the Trace SW inverters, upon blackout the inverters will seamlessly pick up the load and sync with the generator, passing the loads onto the generator after 20 or 30s. While this isn't enough time for the genny to fully warm up, at least the waveforms are in phase which takes a huge strain off the equipment, the genny waveform is stable, and in-rush currents are eliminated. Most transfer switches have a delay of 30 to 60s to allow the genny waveform to stabilize. Sometimes this delay is configurable.

David,

My SMX controllers are programed with the delay.
Hish and I were talking about it earlier this morning. It probably makes sense to leave only the two A/Cs powered through the inverters on when leaving the coach with the Gen auto-start on. Remember, I have 4 A/Cs and 3 SMX controllers. One of the SMX controls 2 A/Cs.

David, it's a balancing act if we have to leave the coach, Keeping our dog "Buddy" cool and treating my generator gently.


Chuck & Tela Millsap
Arizona
2003 Marathon XLII S/S
2000 Wanderlodge LXi S/S
2004 Wanderlodge M380 D/S
2000 Wanderlodge LXi N
/S
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07-08-2017, 15:08 (This post was last modified: 07-08-2017 15:43 by davidbrady.)
Post: #4
RE: Generator Auto-Start
Hi Chuck,

It's interesting how the converters did things differently. You'd think by now, especially considering employee migration from one converter to another, that they'd settle on a standard way to electrically connect things.

My Vantare has four SMXII's and four CruisAirs. All the loads are wired thru the inverters, so the inverters see an accurate picture of the true load drawn by all coach systems. (An advantage of this setup is I can control which of the four CruisAirs the inverters get to power). I have a smart power management system that prunes loads when shore and genny power are lost. Among the items pruned are two CruisAirs. The inverters can power two CruisAirs for up to four hours, depending upon need. Even with all this, I usually make it a rule to leave the coach with only two CruisAirs running. My Trace auto-genny start is always enabled.

With a pet on board, I think having the Auto-Genny start enabled is a must. Each CruisAir consumes around around 2kW. Four of them running is still only half of your generator's capacity, and staggering the compressor start time delay soothes the in-rush current the genny sees. For even better current in-rush control, you can install a soft starter for your CruisAirs. These things are solidstate current limiting devices that hugely reduce current in-rush. Dometic makes one.

david brady,
'02 Wanderlodge LXi 'Smokey' (Sold),
'04 Prevost H3 Vantare 'SpongeBob'

"there is no perfect forum there are only perfect forums"
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07-09-2017, 09:01
Post: #5
RE: Generator Auto-Start
What can possibly be in that box to cost $500! Some just install hard start capacitors to reduce startup Irish current. Hard start caps are nothing more than caps with a slightly greater capacitance.

There are very few conversions that don't have an automatic load shedding scheme. I thought Hoffman was the only one that relied on the owner to proactively shed loads when on inverter power our 30A shore service. Yes, it's on my list to fix.

When in use, I leave the AGS function on. Although it is too shed all loads before switching power sources, I think the Trace 4024 switches faster than any appliance can know there is a switch.

I'm installing new Xanbus controlled inverters and AGS in a bus now. I see that Xantrex is now offering a Xanbus controlled load shedding breaker panel. For some doing an inverter replacement this might be an option.
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07-09-2017, 14:22 (This post was last modified: 07-09-2017 18:09 by cmillsap.)
Post: #6
RE: Generator Auto-Start
(07-08-2017 15:08)davidbrady Wrote:  Hi Chuck,

It's interesting how the converters did things differently. You'd think by now, especially considering employee migration from one converter to another, that they'd settle on a standard way to electrically connect things.

My Vantare has four SMXII's and four CruisAirs. All the loads are wired thru the inverters, so the inverters see an accurate picture of the true load drawn by all coach systems. (An advantage of this setup is I can control which of the four CruisAirs the inverters get to power). I have a smart power management system that prunes loads when shore and genny power are lost. Among the items pruned are two CruisAirs. The inverters can power two CruisAirs for up to four hours, depending upon need. Even with all this, I usually make it a rule to leave the coach with only two CruisAirs running. My Trace auto-genny start is always enabled.

With a pet on board, I think having the Auto-Genny start enabled is a must. Each CruisAir consumes around around 2kW. Four of them running is still only half of your generator's capacity, and staggering the compressor start time delay soothes the in-rush current the genny sees. For even better current in-rush control, you can install a soft starter for your CruisAirs. These things are solidstate current limiting devices that hugely reduce current in-rush. Dometic makes one.

David,
The thermistor for the SMX that controls both bath and bedroom A/Cs is located just in-between the two rooms and the bath is wide open to the bedroom. Also, the 2 A/Cs share the same delivery ducting allowing either A/C or both to cool both rooms. That way 3 A/Cs running will cool all the rooms. I usually only run 3 A/Cs as I can shut off the bedroom A/C or the bath A/C from any one of 3 switches located throughout the coach. Smart thinking by Marathon......


Chuck & Tela Millsap
Arizona
2003 Marathon XLII S/S
2000 Wanderlodge LXi S/S
2004 Wanderlodge M380 D/S
2000 Wanderlodge LXi N
/S
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07-09-2017, 21:12
Post: #7
RE: Generator Auto-Start
(07-09-2017 09:01)CC_Guy Wrote:  What can possibly be in that box to cost $500!

My thoughts exactly! Here's one you can assemble yourself for a couple dollars in parts.

(07-09-2017 14:22)cmillsap Wrote:  Smart thinking by Marathon......

Sounds like a great setup Chuck. I love hearing about the differences between converters.

david brady,
'02 Wanderlodge LXi 'Smokey' (Sold),
'04 Prevost H3 Vantare 'SpongeBob'

"there is no perfect forum there are only perfect forums"
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07-09-2017, 23:19
Post: #8
RE: Generator Auto-Start
Chuck,

I thought a common shared duct was the norm with all roof air supported coaches. At some point, Marathon and possibly others, have deliver ducts dedicated to each roof air.
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07-10-2017, 00:46 (This post was last modified: 07-10-2017 00:48 by cmillsap.)
Post: #9
RE: Generator Auto-Start
(07-09-2017 23:19)CC_Guy Wrote:  Chuck,

I thought a common shared duct was the norm with all roof air supported coaches. At some point, Marathon and possibly others, have deliver ducts dedicated to each roof air.

Yes, CCGuy,

On my Marathon, the front a/c unit has ducting delivering air to the front half of the Salon. There are 4 ceiling duct exits at the front of the Salon. They are located over and behind the driver's & passenger's seats. Probably Marathon designed to keep driver and passenger cooled best.

The (Galley)2nd a/c unit's ducting delivers air to the back half of the Salon as well as the Galley through 6 duct exits with 4 exits in Galley and 2 exits in the back half of the Salon.


Chuck & Tela Millsap
Arizona
2003 Marathon XLII S/S
2000 Wanderlodge LXi S/S
2004 Wanderlodge M380 D/S
2000 Wanderlodge LXi N
/S
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