Snap Shaft Detection - Magnetek Impulse G+ series 4 Instruction Manual

Snap Shaft Detection

This feature is designed to detect a broken or loose coupling by monitoring for a speed deviation
between rotating shafts on a drive train. Ideally, mount one encoder on the motor, which drives the
gearbox and one encoder on the last rotating part of the drive train, usually near the drum if used for
a hoist motion. It is required that a second brake be mounted on the drum shaft. The encoders are
wired into two separate PG-X3 encoder input cards, with channel 1 (CN5-C) being the high speed
shaft input and channel 2 (CN5-B) being the low speed shaft input. The drive will use channel 1 as
the flux vector feedback. The software monitors and compares the speed of both encoders. A gear
ratio is entered into parameters C11-12 and C11-13. In an example, if the gearbox ratio is 46.34 : 1,
then you would program C11-12 to 4634 and C11-13 to 100. If the difference in speed is greater than
the value in C11-10 for a period longer than the setting of C11-11, a "Snap Shaft" is displayed on the
keypad display and the drive will perform the action at snap (C11-09).
Set Up
Parameter U01-30 should be monitored during operation to obtain the exact speed difference in Hz
between the two shafts. The low speed shaft speed is normalized internally by multiplying the speed
of the gear ratio. The value of C11-12 should be adjusted at start up such that U01-30 approaches
0.0.
Parameter
C11-08
C11-09
C11-10
C11-11
C11-12
C11-13
IMPULSE®•G+ & VG+ Series 4 Instruction Manual – February 2017
5-48
Table 5-37: Snap Shaft Parameter Settings
Display Function
Snap Shaft Determines whether snap shaft
detection is enabled.
0 Disabled
1 Enabled
Action at Snap Action taken at detection.
A setting of 0 will set the brake and
0 Brake/Fault Out
display a fault. With a setting of 1,
the drive will continue to run.
1 Alarm Only
Delta Speed Difference in speeds of the two
shafts normalized by the gear
ratio.
Delay Time Gear backlash time in milliseconds 0–2000 ms
Gear Ratio Num Gear ratio numerator
Gear Ratio Den Gear ratio denominator
Range Default Model
0, 1 0 VG+
0, 1 0 VG+
0.0–E01-04 1.0 VG+
Hz
250 VG+
1–65535 10000 VG+
1–65535 10000 VG+