I got an e-mail from someone who wants to know this. (Apparently he thinks I know everything). He’s looking at a DC motor catalog and came across the entry
The only thing I can figure is that it stands for “to be determined,” but that doesn’t make a whole heck of a lot of sense to me when together with “+/- 25%” Using Acronymfinder.com and other searches I come up with these possibilites, none of which makes any more sense to me.
My correspondent seems to think it’s a unit of speed, but he’s not a native speaker of English and I’m not a native speaker of DC motors.
Wow. I thought this would be an easy one, and flipped to Motor Terminology in my WWGrainger catalog. NADA. If you can figure it out, let me know, as I’m curious now.
It’s very commonly put in specs during development, and is supposed to be replaced with the actual number once the product is available. Looks like they missed that number when they released the spec to the public.
I’m with engineer_comp_geek. I suspect that the catalog was a “cut and paste” job by a technical or catalogue writer (think of Elaine Benes on Seinfeld [joke, you tech writers]) and the fact that no actual number was there was missed upon proofreading.
I agree with ecg and David. However, it would be rather pointless and impolite just to submit an ‘me too’ post, so I have to back it up with some additional information.
In the spec writing phase it is (as mentioned earlier) common to write TBD, for any number not defined. If there is a number suggested, but not necessarily agreed upon, it is also common to write that number, followed by TBC, short for To Be Confirmed. Normally these notes should never be in the final document though.
First: Although i would assume that the catalog mentioned was printed in English, i can’t discount the possibility that the catalog was printed in another language. Your reference to your correspondent being a non-native English speaker does cause me to wonder whether the TBD is an English acronym. Additionally, is it possible that the catalog in question is British as opposed to American. It’s possible that the British use the acronym TBD for something other than the standard American meanings.
Second: It is possible that your correspondent is looking for a ‘specialty’ motor; perhaps a motor designed to run slower on start-up (such as a ‘soft-start’ motor) and then progress to a ‘nominal’ speed. The manufacturer may then offer motors with a 25% +/- range once the nominal speed has been defined.
Finally: I could be ignoring occam’s razor and providing possibilities that have not the slightest relation to reality. In the absence of additional information, i’d have to go along with engineer_comp_geek & David Simmons; two posters who have consistently provided technically correct information.