Dynalco DST-2000C Direction Sensing Tachometer - Manual (Page 7)

DST-2000C Instruction Manual 7
1.5 Minimum Speed Requirements
At very low speeds, the amplitude of the output signal from the M343 will be below
the sensitivity level of the DST-2000C. At these low speeds the DST-2000C will not
be able to detect direction of rotation. The output amplitude of the M343 is affected
by the diameter of the gear being sensed and by the air gap between the gear and
the M343. Table 1-1 shows the minimum speed required (in RPM) for the
DST-2000C to detect rotation for a variety of gear diameters at various air gaps.
Gear Dia. 0.005 in. 0.010 in. 0.015 in. 0.020 in. 0.030 in. 0.040 in.
in Inches gap gap gap gap gap gap
4 16 27 40 54 89 160
6 11 18 27 36 59 107
8 8 14 20 27 45 80
10 7 11 16 22 36 64
12 6 9 14 18 30 54
14 5 8 12 16 26 46
16 4 7 10 14 23 40
18 4 6 9 12 20 36
20 4 6 8 11 18 32
22 3 5 8 10 17 29
24 3 5 7 9 15 27
30 3 4 6 8 12 22
36 2 3 5 6 10 18
Table 1-1 Minimum RPM with Gear
1.6 Tach Tape (TT-100)
When using Tach Tape (TT-100) on a shaft, the minimum speeds will be different
than with a gear. Table 1-2 shows the minimum speed required to detect rotation for
a variety of shaft diameters at various air gaps when using TT-100.
Shaft Dia. 0.005 in. 0.010 in. 0.015 in. 0.020 in. 0.003 in. 0.040 in.
in Inches gap gap gap gap gap gap
4 51 68 84 96 127 192
6 35 45 56 64 85 129
8 26 34 43 48 64 97
10 21 28 34 39 51 77
12 18 23 29 32 43 65
14 16 20 25 28 37 55
16 14 18 22 25 32 49
18 13 16 19 22 29 43
20 12 15 18 20 26 39
22 11 13 16 18 24 35
24 10 12 15 17 22 33
30 8 10 12 14 18 26
36 7 9 10 11 15 22
Table 1-2 Minimum RPM with TT-100