Lenze MCH Series - Manual (Page 63)

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The motor overload circuitry is also affected by this parameter. When the display reads
120% load, the drive will trip on OVERLOAD in one minute, regardless of the actual
motor current. If this parameter is used to scale the display to show actual motor load,
then Parameter 17 - MOTOR OL should be left at 100%. Likewise, if MOTOR OL has
been set according to the motor full load rating, this parameter should be left at 100%.
Changing both parameters will result in an OVERLOAD fault sooner than expected.
The output signal at TB-10B is also affected by this parameter. When set to the ratio of
current ratings as explained above, the output signal will be proportional to motor load
instead of drive load.
35
LCD CONTRAST
This parameter is used to adjust the contrast of the drive display and can be set to LOW,
MED or HIGH in order to obtain the most visible display. If the drive is mounted lower
than eye level, a HIGH setting may make the display more visible. Likewise, if the drive
is mounted higher than eye level, a LOW setting may make the display more visible.
36
SLEEP THRSHLD (SLEEP THRESHOLD)
The MCH Series drive has a Sleep Mode function that allows the drive to cease
operation when system demand falls below a preset level. This is to prevent the motor
from operating at low speeds for long periods of time. It is commonly used along with
the PID Setpoint Control feature, but can also be used in standard speed control mode.
When the commanded speed falls below the SLEEP THRESHOLD setting for the
defined SLEEP DELAY time (Parameter 37), the drive will "go to sleep" and the motor
will go to zero speed. The drive will remain "sleeping" until it is commanded to operate
at a speed that is 2 Hz above the SLEEP THRESHOLD, at which point it will "wake up"
and ramp the motor up to the commanded speed.
NOTE 1:
While the the drive is in Sleep Mode, the Status portion of the display will
read SLEEP.
NOTE 2: If the drive's commanded speed goes below the SLEEP THRESHOLD,
the SLEEP DELAY timer will start to count down. If the commanded speed
equals or exceeds the SLEEP THRESHOLD before the SLEEP DELAY
times out, the SLEEP DELAY timer will be reset.
NOTE 3: If the drive is in a Stop state, and the commanded speed is below the
SLEEP THRESHOLD, the drive will immediately go to sleep upon a Start
command, bypassing the SLEEP DELAY.
37 SLEEP DELAY
This parameter sets the amount of time the drive must operate below the SLEEP
THRESHOLD (Parameter 36) before the drive "goes to sleep" and brings the motor to
zero speed.
Example: SLEEP THRESHOLD is set to 15 Hz and SLEEP DELAY is set to 60
seconds. If the drive operates below 15 Hz for 60 seconds, the drive
will "go to sleep" and the motor will stop. The drive's display will indicate
SLEEP, and the drive will remain "sleeping" until the drive is commanded
to a speed equal to or greater than 17 Hz. At this point, the drive will
"wake up" and ramp the motor up to the commanded speed. This example
assumes that SLEEP BANDWIDTH (Parameter 38) is set to 0.