5250 and 30 seem like typos.
NTSC black and white TV scanning frequencies were 60.0 Hz vertical (matched to the power line, has an advantage that any hum in the scan circuits causes a stationary distortion) and 525/2 x 60 = 15750 horizontal. (So, 525/2 = 262.5 lines per field.)
Color kept the same number of lines as black and white, but there was a problem with the color subcarrier - it could be interleaved with the monochrome video or the 4.5 MHz audio, but not both - it just wouldn't work mathematically. The 2nd NTSC decided that moving the 4.5 MHz audio frequency slightly might cause some trouble with existing monochrome receivers, so they moved the scanning frequencies instead, by the exact ratio of 1000/1001. Thus, the vertical became 59.94 and the horizontal became 15734 (15734.2657343... to be more precise).
Since the field rate and frame rate were no longer exact integers, this required the invention of SMPTE "drop-frame" time code. Actually, no frames are dropped, but the count is adjusted periodically so program time in seconds and minutes keeps pace with wall clock time.
https://en.wikipedia.org/wiki/SMPTE_timecode
By the way, since the exact new frequencies including the chroma subcarrier are derived by integer ratios from the old integer values, the ultimate precise chroma frequency is 3579545 + 5/11 Hz, but with a tolerance of +/- 10 Hz. The 5/11 Hz is never called out in standards or FCC regulations, but it comes out that way, as practically all modern broadcast plants are tied to a 10.00000... MHz GPS reference. Before GPS, the major networks for a while used their own atomic clocks, and before that, broadcast gear used oven-controlled crystal oscillators to guarantee the +/- 10 Hz chroma tolerance.
In analog broadcast and professional gear, the chroma frequency and scanning rates are locked to each other. The horizontal scan is the chroma frequency x 2/455; the vertical is the horizontal x 2/525 (i.e., 262.5 lines per field). Digital sources for analog sets (such as DVDs) generally provide these exact numbers, but home VCRs do not lock scan rates to the chroma. In this case, the scan rates are determined by the rotating head speed, while the chroma frequency comes from an independent crystal oscillator. The sound frequency also comes from an independent oscillator. Old video games for analog sets generally use progressive scan with 262 lines per field.