Gen power transfer issue

[#1]

The appliances are not powering up as quickly as they have been after starting my gen. Usually after a couple " coughs", they would go on. Now it's about 8-9 coughs , then they activate. Don't really use it except for in the driveway for maintenance run or on longer trips to keep fridge cold till arrival. I start it regular when not using it and run 20-30 minutes. My questions.
1 why does it take longer all of a sudden to power up appliances?
2 Do I need to shut off stuff before stopping the gen after a maintenance run?
It is a 2013 Cummins Onan 5,500 watt

[MrWizard]

Generator or shore cord, it's the same thing to the transfer switch

Always turn off the large loads like the A/C or electric water heater etc..

Before removing power, and they will be off when you plug in to shore or start the generator

Unplugging or plugging in with loads on will arc and pit the cord blades and the campground outlet

[#3]

Thanks all. It was never related to me, or I forgot, to turn off systems prior to starting or stopping gen. Since I don't use it much, it's one of those things that get neglected on good maintenance. I got it now. Thanks.

[MEXICOWANDERER]

Under load switching is an art-form. And so is generator warm-up.

There is no way in hell I am going to engage my 4 cyl Kubota generator (water cooled) without a full 5 minutes warm up. Air cooled engines require less time for warm up but it would be foolish to try and engage in less than a minute...

Load switching in commercial applications require pumping up an air over hydraulic ram to a certain pressure, then flipping a valve and then the contacts close within a chamber FILLED WITH MERCURY to minimize flashover. Milliseconds count.

I'm going to take a stab at the following

If all load was eliminated on a circuit breaker before engaging it is quite possible to extend it's service life by ten to twenty times. Try 2000%

When loading a generator, always start with the heaviest loads FIRST.

NOT AT THE BREAKER! AT THE APPLIANCE!

Engage the breaker minus all loads, then perhaps the A/C at the air conditioner controls, then kitchen and bathroom...

[enblethen]

Many of the residential breakers are not rated to be used as a switch.
The pedestal breaker should be turned off to prevent arcing.
I would not be shutting off the main breaker in the coach as suggested.

Heavy loads should be shut off before shutting down the genset. It can prevent failure of the voltage regulator in the genset.

[2oldman]

henleyd wrote:
2 Do I need to shut off stuff before stopping the gen after a maintenance run?

Yeah. Also before loading it. You don't start your cold truck on an incline and immediately start up the hill with your heavy trailer.

[WA4HTZ]

Thank you Doug. We just bought a new Winnebago motorhome whit a built-in 2500 Watt generator and I was wondering if turning off the main breaker was the proper thing to do and you just answered my question. Thank you for you sharing your knowledge with the forum.

Ken

[dougrainer]

Explain what you mean by "coughs". The usual Transfer time is about 45 seconds to 1 minute. Once the ATS sees the 120 volts, it starts its timer and after that 45 second delay the Transfer relay closes and then you have 120 power in the RV. COMPLETE 120 power, to all 120 appliances, not just some. The reason you turn off LOADS(appliances) is simple. There are contac points on the Transfer relay's and if you close and open with a load, especially a heavy load, it causes arc'ing of those points and eventually a failure of the points. Most Rv'ers that understand this will turn the inside main breaker OFF when connecting to Shore Power or Genset. Once the shore power is connected or the Genset has come online, they then turn the interior main breaker ON. This helps ATS boxes last a long time. Doug

[pianotuna]

Hi,

As a generator "spins down" the wave form it sends gets wonky and the voltage is too low. Motors and inductive devices do not appreciate that kind of abuse.

According to one of the regulars here, the Champion 3400 inverter generator with remote electric start, does "cut" the power before it spins down. My Pinella remote doesn't do that on my Yamaha 2800.

ksg5000 wrote:
I have always been told to turn off AC appliances before shutting off the generator. Not a science guru so can't tell you why .. but can say I have never heard anyone say otherwise.

[wa8yxm]

Genset as others have suggested does not release power till it is happy. if it is coughing as you call it the unit is not "up to speed" yet. so no joy. Then once it settles in you have the timer in the ATS. it too may be frequency senistive.. i'd make it so if I designed 'em.. Which I don't.

[Jim]

My old '94 Onan 5500 needed to have the slip rings polished occasionally to get better performance and speedier voltage stabilization.

[enblethen]

Genset may have some carbon build up around the choke or the choke is not free due to dirt or whatever. Genset needs to warm enough to stabilize RPMs. Then in some the transfer switch has a time delay.
Turning off genset while under load can cause arcing on the transfer switch relay contacts. This is somewhat like turning off circuit breakers in shore power post before plugging in or unplugging.

[gbopp]

I exercise my Onan 5000 once a month for about 45 minutes under a load.
Do you run your 5500 on a regular basis?

[ksg5000]

My Onan usually takes 10 seconds or so before it releases power to the rig - not sure how that equates to your "cough".

I have always been told to turn off AC appliances before shutting off the generator. Not a science guru so can't tell you why .. but can say I have never heard anyone say otherwise.

[MrWizard]

always turn off things like the A/C and the water heater etc..

before stopping the genny

always start the genny, let it run a minute then turn on loads one by one
largest load ( A/C ) first

not doing this is hard on the generator and the transfer switch
causing arcing of the contacts on the TS, and extreme load on the genny when starting

this has been covered 'hundreds' of times on this forum