Impress your friends by using correct units and abbreviations

[WYtreasure]

@wattmatters Did I get it right?

GVDPR
Grid Voltage Dependent Power Reduction mode: When the inverter simply reduces output in an effort to bring grid voltages down.

 

[Warpspeed]

So what is C ?

Capacitance or the speed of light ?

 

[wattmatters]

GVDPR
Grid Voltage Dependent Power Reduction mode: When the inverter simply reduces output in an effort to bring grid voltages down.

Yes, although I think that specific phrase is used by my brand of inverter - Fronius.

Industry wide here in Australia the the two voltage response modes for the mandatory grid power quality settings are referred to by Standards Australia under the National Electricity Rules as:

Volt-watt
Volt-var

All grid-tied inverters here must comply with the defined settings for each mode at the time of installation.

 

[kanelr]

like professor Mediocratees says...CT

 

[12VoltInstalls]

And the Ω shortcut is "ALT" 234
Along with the ° is "ALT" 0176

Although my iPhone is alt sensitive I hear, unless I remember ascii- 32*F is comprehensive enough isn’t it?

And sometimes KWh -like right there!!! - spell checks (typed kWh) and I give up

 

[12VoltInstalls]

Unit is to number what grammars are to word.

•

 

[WYtreasure]

CME: Coronal Mass Ejection

ICME: Interplanetary Coronal Mass Ejection

CME is a Sun Fart. ICME is a Sun Fart that reaches Earth. More appropriate definitions will influence edits of this post. ?


Some folks are forecasting more of these over the next few years.
Maybe we should consider preparing for these in our solar systems, maybe not. That is a discussion for another thread.

 

[rmaddy]

Although my iPhone is alt sensitive I hear, unless I remember ascii- 32*F is comprehensive enough isn’t it?

For anyone with an iPhone or iPad, hold down the zero key to get the option to enter the degree symbol. Super easy.

And sometimes KWh -like right there!!! - spell checks (typed kWh) and I give up

Strange. I’ve never seen that happen.

 

[stienman]

Ok, but you'll need to give me a terra dollar of cash to get me to use gibibytes.

 

[TerryTtibbs]

How many volts and how many currents is all I ever cared about, nothing else matters really.

 

[Zil]

This is my understanding. Storage Battery capacity is measured by Amp Hours. For deep cycle batteries, Standardized to 20 hours, but I have seen cheaters use 10 hours. It is the measurement of the amperes available and for how long. 100 a/h battery can discharge a steady 5 amperes for 20 hours then it's dead. Watts are a measure of work performed by the current.
And no one has mentioned the abbreviation " I " for current.

 

[rmaddy]

100 a/h battery

Please see post #1. That should be Ah. The use of / means "per" (divided by). It's not amps per hour, it's amp hours which is really short for amps times hours.

 

[wattmatters]

Watts are a measure of work performed by the current.

Sorry to be pedantic but given this is a thread about correct use of terminology...

Watts are not a measure of work. Watts are a unit of power.

Work = energy = integral of power over time.

And power at any given moment = current x voltage.

For a battery, the Ah rating needs to be multiplied by the battery's voltage to provide an energy capacity value. It's this which determines how much work a battery is capable of doing.

The amount of work a battery is capable of performing is of course not a constant as you noted as it depends on the rate the battery is discharged amongst other factors (temperature, age, chemistry, variability of load etc).

 

[TerryTtibbs]

Little V=tingle
Big V=wet your pants
Little A=feel a bit stiff
Big A=MR toasty

I suppose on this basis W=a combination of : - tingle, wet your pants, feel a bit stiff and MR toasty in various degrees.

 

[carbon60]

Yeah, I would love for everyone to move from thinking in Ah to kWh for battery capacity.

 

[Shimmy]

On the style guides saying to put a space between numbers and units-- I hate them. Nothing worse than trying to read a technical publication when you have a number and its units separated with a line break. I understand the argument for the space, but in practical terms it is bunk, especially when your unit is all lower-case.

Is there a common convention for things like kW(PV) on a device that cannot do subscripts?

 

[Benmanji]

The following are common units and their abbreviations. Note that unit abbreviations are case-sensitive. While some units can be understood when written incorrectly, some have a completely different meaning if the wrong case is used. Avoid any possible confusion or ambiguity and use the correct case.

A - amps. Named after André-Marie Ampère.
V - volts. Named after Alessandro Volta.
W - watts. Named after James Watt.
Ω - ohms. Named after Georg Ohm.
h - hours
k - kilo (SI prefix for 1000)
K - Kelvin, a unit of temperature named after William Thomson, 1st Baron Kelvin. Not really relevant in solar discussions.
m - milli (SI prefix for 1/1000)
M - mega (SI prefix for 1000000)

Current is measured in amps - A
A battery's current capacity is measured amp hours - Ah
A battery's energy capacity is measured in watt hours - Wh. Many times it is shortened to kilowatt hours - kWh. Example: 5120Wh or 5.1kWh.
An inverter is measured in watts - W. Many times a value is shortened. 4000W can be written as 4kW. Really large systems could be in megawatts (MW) or even gigawatts (GW).
A battery's voltage is measured in volts - V.
A wire's resistance is measured in ohms - Ω. Many times the resistance is very small such as 0.002Ω commonly written as 2mΩ.

--------------------------

AC vs A/C - AC is alternating current. A/C is air conditioning

--------------------------

While not a unit, one common abbreviation that should be written correctly is for Lithium Iron Phosphate batteries. The correct written form is LiFePO₄ though most people find LiFePO4 is much simpler to type. LFP is a shorthand abbreviation understood in the context of this forum when discussing batteries. Incorrect abbreviations would include LiFePO (lithium iron phosphorus oxide), LiFePo (lithium iron polonium), LiFe (lithium iron). Note that there is a lithium polymer battery typically written as LiPo. That is not at all the same as LiFePO₄. You do not want to confuse the two types. Though both of those types are specific examples of the more general lithium-ion (Li-ion) batteries.

Also
s - seconds
whereas
S - siemens, conductivity (1/ohms)

When I am peer-reviewing documents at work, many times I find myself writing up findings for the issues mentioned above.

Another is adding hyphens such as writing "milli-amperes" instead of milliamperes.

I agree with one of the reply of another user, that there should be a space between the value and its unit, such as using 25 ºC and not 25ºC, but I like how the lack of a space holds information together on one line if it would otherwise be split up by a carriage break, so I tend to let that one slide.

 

[Benmanji]

So what is C ?

Capacitance or the speed of light ?

I believe the speed of light is c (lowercase).

 

[rmaddy]

I agree with one of the reply of another user, that there should be a space between the value and its unit, such as using 25 ºC and not 25ºC, but I like how the lack of a space holds information together on one line if it would otherwise be split up by a carriage break, so I tend to let that one slide.

While I don't personally like a space between a value and its abbreviated units for aesthetic reasons, the use of a non-break space eliminates the issue you mention. When typing a document in a word processor you should be able to enter a non-break space. On a Mac this can be done with option-space. Not sure about Windows, maybe Alt-space. In a web document you can use  . A non-break space prevents the text on either side from being separated across lines.

 

[Benmanji]

While I don't personally like a space between a value and its abbreviated units for aesthetic reasons, the use of a non-break space eliminates the issue you mention. When typing a document in a word processor you should be able to enter a non-break space. On a Mac this can be done with option-space. Not sure about Windows, maybe Alt-space. In a web document you can use  . A non-break space prevents the text on either side from being separated across lines.

Thanks for the reply, as I didn't know that was an option. I looked it up, and for MS-Word it is Ctrl-Shift-Space.