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[genset]

elkangorito, on 2009-11-15 22:39:27, said:

If individual & independent timers are used in each a/c unit, it will not prevent the chance that all or some of the a/c units could start at the same time.

Agreed...

I made reference to this in post #24 in response to Naams initial suggestion of manually turning each AC circuit on, one by one, after generator start up to avoid the AC units starting up 'en masse' (this was prior to the suggestion of using timers, but still applies).

In reality (given that Naam is contemplating a generator sized in an appropriate fashion), this will most probably not be an issue (never say never though...); although the timers would initially provide a delay between the start up of each AC unit after generator startup and transfer to generator supply. As each individual room warms and cools at a variable rate (especially during extended generator run time in the event of a sustained power outage), it becomes increasingly likely that the warming/cooling cycles of the AC units will randomly sync and two or three units (more if you're unlucky) may indeed start up simultaneously.

Genset

Edited by genset, 2009-11-16 00:10:27.

[david96]

Here is some information on AC soft starters suitable for single phase.

http://www.pne.com.a...ts/istart.shtml

Soft starting motor controls will in the future replace many DOL and existing reduced
voltage starters.

[Naam]

thanks David! interesting features but for me extremely confusing. my three ton unit (pool area cooling / pool water heating) is single phase. compressor+indoor fan 4.6 kW and a 1hp circulation pump (total ~5.3kW) start in sync. how the eff can one of my phases which also have at the same time other loads take (acording to the specs of the "soft starter) additional ~160 starting amps?

something seems to be very wrong with all these expert theories of starting amps!

[david96]

Naam, on 2009-11-16 09:37:25, said:

thanks David! interesting features but for me extremely confusing. my three ton unit (pool area cooling / pool water heating) is single phase. compressor+indoor fan 4.6 kW and a 1hp circulation pump (total ~5.3kW) start in sync. how the eff can one of my phases which also have at the same time other loads take (acording to the specs of the "soft starter) additional ~160 starting amps?

something seems to be very wrong with all these expert theories of starting amps!

From that spec regarding the 4.5kW single phase motor

FL Amps @ 230V 23.5A.

With DOL starting 6 FL Amps = 140 Amps. The Blue line on the graph.

With a soft starter the typical starting current is 40 Amps. The dotted red line on the graph.

Starting current is about 1.6 FL Amps of the motor.

[Naam]

my question "additional ~160 starting amps" is still not answered David.

[genset]

david96, on 2009-11-16 07:08:31, said:

Here is some information on AC soft starters suitable for single phase.

http://www.pne.com.a...ts/istart.shtml

Soft starting motor controls will in the future replace many DOL and existing reduced
voltage starters.

Hi David96,

The link and additional information is interesting and the subject of soft starters for AC units may warrant a thread all of its own, I am sure there is interest out there amongst potential users of this technology; but as we have now established that Naams AC units do not feature non-linear/variable speed motors and as this thread exists to provide information and answers related specifically to the installation and operation of generators; I would appreciate very much, if we could please stay on topic and resist the temptation to parse these issues further (beyond the specific concerns of those considering the installation of a generator) within this thread. I'd hate to lose the attention of those with an interest in generators who have read this far...

Genset

Edited by genset, 2009-11-17 05:58:57.

[david96]

Naam, on 2009-11-16 12:56:36, said:

my question "additional ~160 starting amps" is still not answered David.

The 140 amps is the starting current using DOL starting which is what you have at present.

Using an electronic soft starter the starting current is now 40amps. You will not experience
the high starting currents and have smoother starting. See red graph.

Instead of allowing 4 x kVA for motor starting DOL this can be reduced to 2 x kVA for reduced voltage starting of a motor.

The blue line of the graph is a typical 230V 4.5kW DOL starter 6 x FLAmps.
The red broken line of the graph is the same 4.5kW motor but it now has only 1.6 x FLAmps.

The two graphs shown compare the two types of starting, DOL and electronic soft starting.

[stgrhe]

David,

Do you know from where the i-Start AC Motor Soft Starter can be purchased here in Thailand?

[david96]

stgrhe, on 2009-11-17 07:12:52, said:

David,

Do you know from where the i-Start AC Motor Soft Starter can be purchased here in Thailand?

You may have to contact them directly and they will be able to advise you.
Other manufacturers AAB, etc make similiar products and you may have to contact a motor control distributor in Thailand.

[maccaroni man]

i dont know if i can get an answer for our needs but one camn only hope. our house has a mote running around it for the periods of high rain, currently we have a sub pump that empties all the holding tanks once i plug it in. our engineer has suggested that i get a sub pump with a float valve however i think it is as important to get a port gen because if the power goes off no matter what type of pump i have it will not help.

what size gen should i consider buying for a small job such as this? what specs should i consider most? what price should i expect to pay in bkk?

[Naam]

david96, on 2009-11-17 05:47:29, said:

Naam, on 2009-11-16 12:56:36, said:

my question "additional ~160 starting amps" is still not answered David.

The 140 amps is the starting current using DOL starting which is what you have at present. Using an electronic soft starter the starting current is now 40amps. You will not experience the high starting currents and have smoother starting. See red graph.

David,
i am copying now slowly again what my question was. perhaps you could read it slowly, understand what i meant and answer it slowly instead of referring to some "DOL"?

my question is now also directed to Genset, ElKangorito and Crossy.

my three ton unit (pool area cooling / pool water heating) is single phase. compressor+indoor fan 4.6 kW and a 1hp circulation pump (total ~5.3kW) start in sync. how the eff can one of my phases which also have at the same time other loads take (according to the specs of the "soft starter) additional ~160 starting amps?

something seems to be very wrong with all these expert theories of starting amps!

[Gary A]

At the time I was involved with big motors in a factory, the only soft start units available were for three phase. Since most of the big motors were three phase, it made very little difference for our usage.

ADDDED - The soft start units worked great.

Edited by Gary A, 2009-11-17 08:53:56.

[david96]

Naam, on 2009-11-17 09:26:58, said:

david96, on 2009-11-17 05:47:29, said:

Naam, on 2009-11-16 12:56:36, said:

my question "additional ~160 starting amps" is still not answered David.

The 140 amps is the starting current using DOL starting which is what you have at present. Using an electronic soft starter the starting current is now 40amps. You will not experience the high starting currents and have smoother starting. See red graph.

David,
i am copying now slowly again what my question was. perhaps you could read it slowly, understand what i meant and answer it slowly instead of referring to some "DOL"?

my question is now also directed to Genset, ElKangorito and Crossy.

my three ton unit (pool area cooling / pool water heating) is single phase. compressor+indoor fan 4.6 kW and a 1hp circulation pump (total ~5.3kW) start in sync. how the eff can one of my phases which also have at the same time other loads take (according to the specs of the "soft starter) additional ~160 starting amps?

something seems to be very wrong with all these expert theories of starting amps!

Your total load as connected is 5.35kW single phase. 1 x 4.6kW and 1 x 0.75kW

The 4.6kW motor is the only one connected to the soft starter. The 0.75kW motor remains connected DOL.

All other loads on the same phase must not be connected to this starter and may remain as DOL starting. You could upgrade these if you wish to soft starters if you want to further reduce you starting currents on your system depending on the size of the motors.

One soft starter to one motor.

DOL = direct on line, full voltage starting.
Reduced voltage starting = the soft starter in this case.

[elkangorito]

Naam, on 2009-11-16 08:37:25, said:

how the eff can one of my phases which also have at the same time other loads take (acording to the specs of the "soft starter) additional ~160 starting amps?

something seems to be very wrong with all these expert theories of starting amps!

Hi Doc.

The size of a cable is not determined by the starting current of motors etc. These temporary high currents are ignored because they do not significantly increase the heat produced in a cable. Of course, this is under "normal" conditions. "Abnormal" conditions would be if the total load of an entire installation consisted of motors that frequently stopped & started. In such a case, the inrush currents may have a significant heating affect on cables & therefore, such cables may need to be derated.

Is this the answer you are looking for?

[genset]

maccaroni man, on 2009-11-17 09:15:18, said:

what size gen should i consider buying for a small job such as this? what specs should i consider most? what price should i expect to pay in bkk?

Hi Maccaroni Man,

If you have some spare time, try to read through the thread from start to finish, there is a lot of information within, regarding machine specs and prices for the Kipor range I am promoting.

It sounds like you havent purchased the pump yet; decide which pump best suits your needs and base your generator size on the power requirements of the pump you purchase (again, there are references to calculating generator size according to your load requirement within the thread).

Genset.

[Naam]

The 4.6kW motor is the only one connected to the soft starter. The 0.75kW motor remains connected DOL.

NOTHING in my home is connected to some "soft starter" and i have no fücking idea who or what a DOL is let's leave the subject as it is and i will die as stupid as i am now.

[Naam]

elkangorito, on 2009-11-17 11:44:48, said:

Naam, on 2009-11-16 08:37:25, said:

how the eff can one of my phases which also have at the same time other loads take (acording to the specs of the "soft starter) additional ~160 starting amps?
something seems to be very wrong with all these expert theories of starting amps!

Hi Doc.
The size of a cable is not determined by the starting current of motors etc. These temporary high currents are ignored because they do not significantly increase the heat produced in a cable. Of course, this is under "normal" conditions. "Abnormal" conditions would be if the total load of an entire installation consisted of motors that frequently stopped & started. In such a case, the inrush currents may have a significant heating affect on cables & therefore, such cables may need to be derated.

Is this the answer you are looking for?

NO Señor Kang! i was not referring to some bloody cable. i wanted to have an answer how one phase of my electrical installation is able to handle besides some normal running amps (perhaps 15) the additional starting amps of my 36k btu pool cooler/heater and its water pump if the factor is 3 or even 4.

i obviously don't know how to phrase my question properly that you native speakers understand me and my wife seems to be right as she is telling me since nearly 35 years that my english is rather poor. she is returning to Thailand on monday and then i will beat her up for not teaching me correct english

but to shame you all i will ask my next question in either arabic, urdu, farsi or high bavarian!

[david96]

Naam, on 2009-11-17 19:02:26, said:

The 4.6kW motor is the only one connected to the soft starter. The 0.75kW motor remains connected DOL.

NOTHING in my home is connected to some "soft starter" and i have no fücking idea who or what a DOL is let's leave the subject as it is and i will die as stupid as i am now.

Your existing connection.
1 x 4.6kW motor connected for DOL , 1 x0.75kW DOL. plus other motor loads including
other airconditioners.

If you were to connect an electronic soft starter as an option to reduce starting current
this would be connected to the 4.6kW motor. this is your largest individual motor.

DOL direct on line starting means full voltage starting and max locked rotor current
6 x FLA of the motor. With the soft starter starting currents are reduced to 1.6 x FLA.

The advantages of a soft starter with a motor are, reduced starting currents, smooth starting, full motor protection and a reduction in generator set capacity for starting purposes.They also have provision for time delay starting on reinstatement of power.

To prevent all your other airconditioner motors starting at once time on reinstatement of power supply, time delay relays may be fitted to each airconditioner with the time for each unit between 180 secs with 30 secs increments as an example. This is known as auto reset.

Alternatively a standard relay may be used and manually reset by means of a push button on
each unit. The relays can be mounted adjacent to the equipment in an enclosure.

An example of delay timing sequence auto reset.
Aircon 1. 180 secs.
Aircon 2. 210 secs.
Aircon 3. 340 secs.
Aircon 4. 370 secs.

[david96]

Naam, on 2009-11-17 19:14:49, said:

elkangorito, on 2009-11-17 11:44:48, said:

Naam, on 2009-11-16 08:37:25, said:

how the eff can one of my phases which also have at the same time other loads take (acording to the specs of the "soft starter) additional ~160 starting amps?
something seems to be very wrong with all these expert theories of starting amps!

Hi Doc.
The size of a cable is not determined by the starting current of motors etc. These temporary high currents are ignored because they do not significantly increase the heat produced in a cable. Of course, this is under "normal" conditions. "Abnormal" conditions would be if the total load of an entire installation consisted of motors that frequently stopped & started. In such a case, the inrush currents may have a significant heating affect on cables & therefore, such cables may need to be derated.

Is this the answer you are looking for?

NO Señor Kang! i was not referring to some bloody cable. i wanted to have an answer how one phase of my electrical installation is able to handle besides some normal running amps (perhaps 15) the additional starting amps of my 36k btu pool cooler/heater and its water pump if the factor is 3 or even 4.

i obviously don't know how to phrase my question properly that you native speakers understand me and my wife seems to be right as she is telling me since nearly 35 years that my english is rather poor. she is returning to Thailand on monday and then i will beat her up for not teaching me correct english

but to shame you all i will ask my next question in either arabic, urdu, farsi or high bavarian!

To show the effect of having a reduced voltage starter (soft starter) on the size of a genset.

Example 1: A 3 phase 380V 7.5kW 13.6A motor to be connected to a genset.

Using DOL starting the starting current would be 6 x 13.6 = 81.6A.
Additional generator capacity for motor starting. 4 x 13.6 = 54.4A

Generator requirements 36kVA. = 380V x 54.4A x 1.732

With a soft starter the starting current could be as low as 1.6 x 13.6 = 21.76A
Additional generator capacity for motor starting. 2 x 13.6 = 27.2A

Generator requirements 18kVA. = 380V x 27.2A x 1.732

Example 2: A single phase 220V 4kW motor, an airconditioner.
Using DOL starting the starting current would be 6 x 21.8 = 130A
Additional generator capacity for motor starting.4 x 21.8 = 87.2A

Generator requirements 19.2kVA = 220 x 87.2

With a soft starter the starting current could be as low as 1.6 x 21.8 = 34.9A
Additional generator capacity for motor starting. 2 x 21.8 = 43.6A

Generator requirements 9.6kVA = 220 x 43.6

Advantages of soft starter.
Low starting currents , smooth starting, full motor protection, reduction in genset capacity.

Costs. Cost of a soft starter against the cost of a larger genset. And if you have a larger genset you have spare capacity in kVA for other purposes.

[Crossy]

Naam, on 2009-11-17 20:02:26, said:

NOTHING in my home is connected to some "soft starter" and i have no idea who or what a DOL is

'DOL' = Direct On Line, in this context simply means connecting the motor to the mains with no soft starter

[Marvo]

Naam, on 2009-11-16 08:37:25, said:

thanks David! interesting features but for me extremely confusing. my three ton unit (pool area cooling / pool water heating) is single phase. compressor+indoor fan 4.6 kW and a 1hp circulation pump (total ~5.3kW) start in sync. how the eff can one of my phases which also have at the same time other loads take (acording to the specs of the "soft starter) additional ~160 starting amps?

something seems to be very wrong with all these expert theories of starting amps!

What size / rating circuit breaker do you have on that circuit naam, that 160+ amps being drawn doesn't trip?

[Naam]

David,
thanks to your explanations i am well aware what the function of a soft starter is. but the question i asked has nothing to do with any soft starter. anyway, the question is academic and not really relevant for the problems which have to be solved and "Genset" was kind enough to answer it.

i also want to keep my installation as simple as possible that in case of a problem either myself or a qualified electrician can lay a hand on. anything that contains chips or is computerised should in my view be avoided when living in the technical wilderness of Thailand. member "Genset" has sent to me by mail the description of a most beautiful gadget which would handle automatic/remote start-up in case of brownouts or phase failures. however, i prefer a simple approach and tend to have a remote but manual generator start and switching on manually whatever consumers i need, respectively what the selected generator can handle. that of course does not rule out the use of soft starters, especially for the aircons.

additional second thoughts have also come up as far as a 3-phase generator is concerned. i normally face a brownout or complete loss of a single phase only and have still two phases with normal voltage. therefore i think it's an economical nonsense to switch off the "good" phases too and serve all three phases with a 3-phase generator.

it should be possible to have the (single phase) generator switch to any of the phases in my house as needed. i had a similar but very simple setup in a house (in another "high-tech" country) decades ago. the house was wired single phase but we had a 3-phase incoming supply and used whatever phase was "on" or delivering the correct voltage.

opinions please and thanks in advance.

[Naam]

Marvo, on 2009-11-18 10:41:02, said:

Naam, on 2009-11-16 08:37:25, said:

thanks David! interesting features but for me extremely confusing. my three ton unit (pool area cooling / pool water heating) is single phase. compressor+indoor fan 4.6 kW and a 1hp circulation pump (total ~5.3kW) start in sync. how the eff can one of my phases which also have at the same time other loads take (acording to the specs of the "soft starter) additional ~160 starting amps?

something seems to be very wrong with all these expert theories of starting amps!

What size / rating circuit breaker do you have on that circuit naam, that 160+ amps being drawn doesn't trip?

a freaking normal Siemens 'lazy' 25 amp breaker which has never tripped and that is the reason why i doubt all these starting factors 3 and 4

[Marvo]

Naam, on 2009-11-18 11:09:34, said:

What size / rating circuit breaker do you have on that circuit naam, that 160+ amps being drawn doesn't trip?

a freaking normal Siemens 'lazy' 25 amp breaker which has never tripped and that is the reason why i doubt all these starting factors 3 and 4

In my photo studio we used the big Bowens capacitor power packs which claimed to have a peak draw rated at 15amps. We would run two of these plugged into a 13amp extension lead protected by a 13 amp fuse, and a total of six or seven on a 30amp ring main. Never a problem. I know it's not motors which is what we're talking about in this thread, but this Quoted Max/Peak drawn current business baffles me too.

[Crossy]

Naam, on 2009-11-18 11:59:43, said:

it should be possible to have the (single phase) generator switch to any of the phases in my house as needed. i had a similar but very simple setup in a house (in another "high-tech" country) decades ago. the house was wired single phase but we had a 3-phase incoming supply and used whatever phase was "on" or delivering the correct voltage.

Do you have any 3-phase equipment? If so forget trying to feed one phase off a non-synchronised genset, 3-phase motors would get more than somewhat upset

Otherwise, if you've actually got what amounts to 3 single-phase installations I see no reason why (with appropriate interlocks and safety devices) you shouldn't feed one or more phases from your genset, leaving the 'good' phase powering the remaining kit. How legal this would be in Oz or the UK I don't know, not very I would suspect.