Set Of Pumps Vs Gen-set rating 1

[Zack68]

Hello All,

I have set of different rating sub-pums used in smart Faunten work, the total electrical load is 450 KW.
What would be the main CKT Breaker rate and its type ? and what is the generator ration goes with this let say if there is a possibility all pumps are working at the same time.

Thank you ,,

 

[GroovyGuy]

hi zack,
Need some additional info;
1) what is quantity & size (ie motor hp) of these pumps?
2) type of pump (ie centrifugal or constant displacement)?
3) is there ant (process) requirement for VFDs (or can they be full-voltage or reduced-voltage started)?
4) what is "smart Faunten work"?
GG

"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)

 

[Zack68]

GG, Thank you for your kind response..

1) what is quantity & size (ie motor hp) of these pumps? 20X15Hp, 10X5Hp, 30X3Hp
2) type of pump (ie centrifugal or constant displacement)?centrifugal
3) is there ant (process) requirement for VFDs (or can they be full-voltage or reduced-voltage started)? Full Voltage Started
4) what is "smart Faunten work"? the idea is, the pumps would be controlled by music equalizer and the on/off for each pump based on it sequence in this music pattern. but there is like common background ALWAYS ON like 10X15 HP pumps.

Rating 380V/50Hz
Generator consider the main Power Supply for a while.

Thank you again .. Best!

 

[GroovyGuy]

Hi Zack.
Based upon your load profile above, the maximum demand will be 440hp (or approx. 375kW). This assumes that all pumps are running at full-load, along with a nominal motor efficiency.
Generally, one does not want to run a generator continuously above 80% of it's power rating, therefore required gen-set should have a power rating of 470kW. Rounding up to the next commercial size (say): 500kW 625kVA

A 625kVA 380V gen-set will likely have a (minimum) 1000A 100% CB, although it may be one size larger.
Q1: How many hours per year will the gen-set be required to run at the max power level? (ie You also need to determine if the gen-set will be standby, continuous or prime power rated.)
Q2: What is the fuel-source for the gen-set (ie diesel or natural gas)?
GG


"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)

 

[EdStainless]

The other detail is how many of the pumps will turn on at the same time?
Inrush current on start of the 15hp could be a concern.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[GroovyGuy]

Good point Ed,
I had assumed that the motors would not be started at the same time. Perhaps Zack could comment on that issue?
I would not worry wrt to starting a single 15hp motor, it will have a negligible impact on the generator to accelerate the motor. However, simultaneously starting 10 (15hp motors) might be an issue.
GG

"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)

 

[waross]

Take the sum of the motor currents. Add twice the sum of the currents of all the motors that may start simultaneously.
This will give you the minimum generator current capacity.
Said another way;
The sum of all the motors running plus three times the sum of the next group of motors to start.

Order the generator with the PMG (Permanent Magnet Generator) option. The PMG powers the Automatic Voltage Regulator (AVR) and gives better motor starting performance.
A Naturally Aspirated engine better than load often takes block loading better than a Turbo Aspirated engine.
You are safer to consider current ratings than HP ratings, kW ratings or KVA ratings.
We ordered a 75 KVA set at 208 Volts. Rated current 208 Amps.
The supplier shipped a 75 KVA set at 240 Volts. Rated current 180 Amps.
The set would not pull the load.
Sending the set back to the supplier is often not an option when ocean shipping is involved.
If the set is standby rated you may want to check the RMS loading.
If the set is prime power rated it will be 25% oversized and there is no need to worry about 100% loading.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ScottyUK]

Register to use CAT's SpecSizer tool.

https://specsizer.cat.com/

You can look at different scenarios such as sequential start, simultaneous starting of all drives, block loading of groups of drives, etc. It's fairly intuitive. Results are generally a little conservative.

 

[waross]

Register to use CAT's SpecSizer tool.

https://specsizer.cat.com/

.......
Results are generally a little conservative.

Many years ago I was selecting and installing residential standby sets.I did about 8 sets in a short period of time.
All of the sites had multiple air conditioners. All of the installations worked well and all of the customers were happy.
Some years later the first version of Specsizer became available.
I ran the parameters of the existing installations through Specsizer and ALL FAILED.
Why?
Specsizer is excellent software. Why is it failing successful installations.
I believe that it has to do with the default settings.
If you want performance equal to grid performance, use the default settings.
Most applications and most customers will accept a greater voltage dip on a generator than when on the grid.
One of the reasons for the conservative results returned by Specsizer may be the default setting for allowable voltage dip.
Try increasing the setting for allowable voltage drop in Specsizer. It may save you several thousands of dollars on the price of the set.
I would do an RMS loading analysis of the load profile. If the RMS loading is much less than the peak loading then you may consider using a standby rated set.

Will the generator be used for standby service or will the generator be the prime source of power?
If the generator is to be the main source of power, how long will it be in service?
If the installation calls for permanent generator power, a prime power rated set would normally be selected.
However it appears that your load will be highly variable.

As a consultant, at this point I would be asking my customer;
"Why do you want a generator?"
Decorative fountains are not normally supplied with back-up power.
If a generator is being considered because of the high cost of installing grid power, A generator often costs more.
I worked in an area where grid power was diesel generated and was very expensive.
Many homes had standby generators. The cost of grid power was about twice the cost of fuel to run a standby set.
But fuel cost is not the only cost of running a generator. There is the cost of oil changes and repairs. There is the cost of overhauls and/or eventual replacement of the gen-set. There is the consideration of a possible lengthy power outage in the event of a gen-set failure.
All things considered no-one ever considered running their sets full time despite the up-front apparent advantage of 50% cost of running.
How much will it cost to run a generator?
The cost per hour may be estimated:
You can expect to generate 13 kWHrs per US gallon of diesel fuel. Double this figure to get an idea of the hidden costs.
Oh, by the way, that is for a loaded set. The fuel consumption per kWHr increases for a lightly loaded set.



Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ScottyUK]

Hey Bill, I said "... results are a little conservative."

In my experience of Specsizer for industrial applications (primarily motor loads) almost every load scenario is alternator / AVR limited rather than engine-limited, and I agree with Bill's suggestion to open up the voltage window from default settings if your load will handle it. Watch for contactor drop-out voltage though.

I also see things from CAT's perspective:
[ul]
[li]CAT don't want to be sued for selling a set which doesn't meet the performance predicted by their own software. I think there's some margin built in for age-related engine degradation.[/li]
[li]Specsizer assumes that everything is worst case, every time. Even I don't have luck that bad.[/li]
[li]CAT are in the business of selling gensets. Why sell you a smaller one if they can sell you a bigger one?[/li]
[/ul]


As another indicative guide on fuel burn, a 1000kW / 1250kVA set continuously running near full load will burn roughly an artic (semi-trailer) tanker per week. That's lot of fuel to manage.

 

[Zack68]

Thank You gentlemen for your participating,

Actually, the set of the pumps used for the dancing fountain system, means the pumps operation controlled by PCB based on musical background program(s). the 10X15Hp will be started with seconds duration apart the others has different sequence,
My question now, are the pumps used in such system are the same with the ordeneray once since they need pulsating operation?ea
This system would be installed in the water play area and there is 8 hrs out of power for the first two years.
How about this short cut method convert all Hp to Kw then the total X 2 = the current @ full load. then
we can get the approximate genset required.
Please advice..

Best
Zack

 

[waross]

How about running the pumps continuously and controlling the water with solenoid valves? If you then start the largest pumps first, and stagger the starts you can use the bare minimum generator size.
That looks like 5000 to 6000 Hours on the set.
If you are sizing the set exactly, you may be under powered by the end of 6000 hours.
Also there is the issue of fuel Specific Density.
If you get a load of light fuel you may need more engine capacity.
Switching the water with solenoids and stagger starting the pumps will require the smallest gen-set. If you ho this route I suggest going 25% over on generator capacity. That will give you a cusion in the event that one large pump must be started with the other pumps already running, it will cover you for "light fuel" events and it will allow for some loss of power as the hours build up on the set.
Are you subject to very cold winters?
If this is outdoors in a cold area I expect that it will be shut down in freezing weather.
If this is indoors in a cold climate, you may receive winter grade fuel in the winter months. Expect to lose at least 10% of your maximum output on winter fuel.
Even in the summer in a cold climate area, you may inadvertently get a load of winter grade fuel in the warmer months.



Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Zack68]

Thank you Bill,

water reserve + solenoid valve would be perfect idea in this case we have to figure out the cretin pumps/reserves configuration cover wide range of programs..
You mentioned the gen-set capacity would be around (+25% of the Total load )based on this operation and staggering start up.. but how about the pressure dropped in reserves feeding from 15Hp pumps, can I controlled by the pressure-state set it in frictional pressure difference than other reserves? in this case the fountain solenoid valve doesn't affect and we still maintain the right gen set size with no surprises.

Best!

Zack

 

[waross]

We don't know anything about the required flows and pressures and if the pressure is critical.
You should design this from a pumping standpoint if you are going to use solenoids.
Perhaps the 5HP pumps and the 3HP pumps may be replaced with one or more larger pumps.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[EdStainless]

I have seen fountains that are fed from a ring header, the water is supplied by 3 or 4 larger pumps on VFDs.
These kept the header supply at a roughly constant pressure, all of the display was controlled by valves.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[NCTHAI]

You can easily control the pressure and flow pattern by shape and size of the nozzle. With generator, one or two pump and array of solenoids for ON / OFF control, what you will have is single header with constant pressure. In order to make fountain dance you need nozzle of different size and shape. This is the optimal solution. Don't forget about the minimum flow requirement of pump and allow pressure relief from header in case of pressure increases above desired / safe pressure limits.

NC