Magnetek DSD 412, Техническое руководство

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DRIVE SETUP
72
Using The Notch Filter
Some hoist ways may have rope resonance’s
that cause occasional vibrations, roughness
of ride or continuous oscillations at certain
low frequencies. There may be critical
hoistway locations or payload weight
combinations that tend to be more sensitive
than others. The effects are often felt rather
than heard. The frequency sensitive notch
filter, placed in the software path of the
torque / armature current reference signal,
can be effective to suppress the response of
the DSD 412 drive to amplify those
frequencies. Adjustments for this filter are via
#191, the period, or center frequency of the
filter, and #190, the depth of the notch, or its
ability to attenuate. Use the filter as follows:
Determine the approximate frequency of the
oscillations or rope ‘ringing’.
Use Table 8 #191 to set a center frequency
value slightly higher than that of the observed
disturbance. The default value of 7 (12 Hz)
will be sufficient in many cases.
Increase the value of #190 to suppress the
tendency to respond or amplify rope
resonance.
CAUTION: Be aware that the ability of the
drive to follow the speed commanded by the
car controller is altered by these adjustments.
If the frequency of the filter is set too low, or
the notch depth is set too deep, there may be
interference problems associated with
operating the closed loop velocity regulator or
position control loops within the Car
Controller. Typical symptoms would include
position overshoot of floor landings and
potentially repetitive speed oscillations or
speed ‘hunting’. If these symptoms occur,
back off on the Notch Depth setting #190
and/or reduce the setting of #191 (Notch
Period), increasing the notch center
frequency to avoid interference.
Motor Overload
Motor armature current is sensed and
mathematically integrated over time to detect
potential over heating caused by a dragging brake
shoe or other repeated abuse beyond ratings of
the equipment. The calculation formula used for
the electronic motor overload is:
) ( 2 Ko i T t
− =
Where:
t = Calculated time to trip in seconds
i = Measured Per Unit motor current. Drive Param
#3 defines motor Per Unit current in amperes.
T = Time to trip setting #83 at motor current of
(Ko+0.5) per unit current.
Ko = Maximum Per Unit current that will not cause
an Overload Trip #84.
The USA National Electric Code (NEC) requires
that the overload be adjusted to detect
overheating of the motor and motor wiring by
using rated motor current as the comparison base.
This is not the same as rated current capability of
the drive. The NEC requirement is that the
overload must trip at 1.15 Pu current (no time
specified), and after 60 seconds at 1.5 Pu current,
and after 10 seconds at 2 Pu current. It is
recommended that the default values of Ko=1.1
and T=50 be used. This will provide no tripping
with average motor current of 1.1 Pu or less, and a
tripping time of 62 sec at 1.5 Pu. See the timing
graph of Figure 18: Motor Overload
MOTOR OVERLOAD, Ko=1.1, T=50
Figure 18: Motor Overload
Overload Trip Time
Ko=1.1, To=50
0.0
50.0
100.0
150.0
200.0
1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8
Per Unit Current
S
e
c
onds