EGCP-2 Engine Generator Control Package Manual 26076
26 Woodward
MPU (Speed) Input
To sense engine speed, the control accepts signals from one passive magnetic
pickup unit (MPU) mounted off of a gear, which is connected or coupled to the
engine’s main shaft.
A passive MPU provides a frequency output signal corresponding to engine
speed by sensing the movement of a gear’s teeth past the MPU’s pole piece.
The closer the MPU’s pole piece is to a gear’s teeth and the faster the gear turns
the higher a passive MPU’s output amplitude will be. The EGCP-2 must sense
an MPU voltage of 2 to 25 Vrms for proper operation.
MPU Input Ratings
Low frequency range: 100–250 Hz @ 3.5 to 25 Vrms
Normal Frequency Range: 250–15 000 Hz @ 2.0 to 25 Vrms
Input impedance: 15 000
With proper MPU, gear size, and MPU-to-gear clearance, speed measurement
should be capable down to 100 Hz. Standard MPU clearance is recommended to
be .010” to .040” from tooth face to pole piece. For information on selecting the
correct MPU or gear size please refer to Woodward manual 82510. See Figure
3-12 for wiring schematic.
MPU
Magnetic Pickup Unit
200 - 3K ohms impedance
70
71
(-)
(+)
1000pF
1000pF
4.99K
4.99K
4.99K
VIS-051b
01-03-18
Figure 3-12. Wiring Diagram for MPU Input
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