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How to understand synchronism?

How to understand synchronism?

How to understand synchronism?

(OP)
I'm not an electrical engineer, but an environmental/process guy.
In my job, I frequently compile a rough rundown of the power consumption of simple industrial plants. Here, you always encounter a "synchronism" factor, besides how many motors of which power are installed and the expexted run-time (min/h). The rest I understand, but how is synchronism defined and how do I find it?
I understand this to mean how many motors are likely to run at the same time, to correctly size the power supply for the plant. But I do not know how to calculate it.

Our EEs are notoriously hard to catch, so I ask here.

RE: How to understand synchronism?

I'm not sure 'synchronism' is the correct term for what you are trying to describe, although I think I know what you're talking about. Synchronism is a condition required for a generator to operate in parallel with a larger system or in parallel with other generators, or for two systems to be able to be safely connected together. Synchronism is achieved when the two sources are matched in voltage, frequency, phase rotation and phase angle. When two sources are synchronised you could, in principle, connect them together without any current flowing between them.

What I think you're describing is 'diversity', which is a method of estimating the real-world load of an installation by estimating the probability that any individual load will be energised simultaneously with other loads, rather than simply adding up all the nameplate values of the loads. The latter method usually results in equipment being over-sized by a ridiculous factor. Now you know the name of what you are looking for, Google is your friend: have a look for electrical diversity calculation. Bear in mind that diversity factors for process plant will need some input from your process engineers, although for simple stuff like duty/standby pumps you can probably use a 0.5 factor with reasonable comfort.

RE: How to understand synchronism?

(OP)
Thanks a lot! I miss-translated the german term 'Gleichzeitigkeitsfaktor'

RE: How to understand synchronism?

The demand, (the maximum usage during a given time period, often a month, or the usage at any one time) may be what you are looking for.
This varies greatly. Plant scheduling and mode of operation along with other factors affect the diversity, or ratio of usage to maximum installed capacity.
Some designers may run the motors at or slightly above the HP rating and others may choose to use a larger motor for the same load.
In North America I have several times gone to the accounting department and requested copies of the power bills for the last year or two. The bills here show the maximum demand for each month, for large plants.
Further to Scotty's post:
On a design for a small wood working plant the main transformer could either be owned by the utility or the client. This was mostly an economic decision, however if the client owned the transformer it must be sized as per the Canadian Electrical Code and was roughly 1 KVA per HP. If the utility owned the transformer they would use their experience with similar plants and size the transformer at 0.5 KVA per HP.
The demand or diversity calculations are based more on art than science. Past history, experience, and allowances for unique operating conditions are often the best tools for forecasting the demand.
Oh and consumption is measured in Kilo-Watt-hours (KWHrs). Demand is measured in Kilo-Volt-Amperes (KVA).
I'll sign off now before the froth on the beer gets too deep. grin

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

RE: How to understand synchronism?

(OP)
Waross, this is helpful - esp. knowing that it's more about art than science.

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