Magnetek IMPULSE G+ 4 Series User Manual

IMPULSE
®
•G+ & VG+ Series 4 Technical Manual
November 2020
Page 112
5.2.21 Snap Shaft Detection
This IMPULSE
®
•VG+ Series 4 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 VFD 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 VFD will perform the action at snap (C11-09).
5.2.21.1 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.
Table 5-37: Snap Shaft Parameter Settings
C11-05 SLC Delay Time 1 The delay time before the enabled Slack Cable
Detection can be activated. It corresponds to
Slack Cable Detection Speed 1 (C11-04).
Prevents false outputs.
0.00–2.55 sec. 0.50
C11-06 SLC Detect Spd 2 The Frequency Output below which the enabled
Slack Cable Detection can be activated. It
corresponds to Slack Cable Detection Delay Time
2 (C11-07).
0–E01-04 Hz 60
C11-07 SLC Delay Time 2
The delay time before the enabled Slack Cable
Detection can be activated. It corresponds to Slack
Cable Detection Speed 2 (C11-06). Prevents false
outputs.
0.00–2.55 sec. 0.10
Parameter Display Function Range Default
C11-08 Snap Shaft Determines whether snap shaft detection is
enabled.
0, 1 0
0 Disabled
2 Enabled
C11-09 Action at Snap Action taken at detection.
A setting of 0 will set the brake and display a fault.
With a setting of 1, the VFD will continue to run.
0, 1 0
0 Brake/Fault Out
1 Alarm Only
C11-10 Delta Speed Difference in speeds of the two shafts normalized
by the gear ratio.
0.0–E01-04 Hz 1.0
C11-11 Delay Time Gear backlash time in milliseconds 0–2000 ms 250
C11-12 Gear Ratio Num Gear ratio numerator 1–65535 10000
C11-13 Gear Ratio Den Gear ratio denominator 1–65535 10000
Parameter Display Function Range Default

Magnetek IMPULSE G+ 4 Series Specifications

General

Brand	Magnetek
Model	IMPULSE G+ 4 Series
Category	DC Drives
Language	English