TECO F33 Series, Инструкция по эксплуатации, Страница: 41 / 192

38 Main Features
7.5 Load Monitor and Process
Protection [400]
7.5.1 Load Monitor [410]
The monitor functions enable the VSD to be used as a
load monitor. Load monitors are used to protect
machines and processes against mechanical overload
and underload, such as a conveyer belt or screw con-
veyer jamming, belt failure on a fan or a pump dry run-
ning. The load is measured in the VSD by the calculated
motor shaft torque. There is an overload alarm (Max
Alarm and Max Pre-Alarm) and an underload alarm
(Min Alarm and Min Pre-Alarm).
The Basic Monitor type uses fixed levels for overload
and underload (pre-)alarms over the whole speed
range. This function can be used in constant load appli-
cations where the torque is not dependent on the
speed, e.g. conveyor belt, displacement pump, screw
pump, etc.
For applications with a torque that is dependent on the
speed, the Load Curve monitor type is preferred. By
measuring the actual load curve of the process, charac-
teristically over the range of minimum speed to maxi-
mum speed, an accurate protection at any speed can
be established.
The max and min alarm can be set for a trip condition.
The pre-alarms act as a warning condition. All the
alarms can be monitored on the digital or relay outputs.
The autoset function automatically sets the 4 alarm lev-
els whilst running: maximum alarm, maximum pre-
alarm, minimum alarm and minimum pre-alarm.
Fig. 44 gives an example of the monitor functions for
constant torque applications