Revolutions control module regulates work power of AC motor,
using phase shift. This control method is not so sophisticated
as frequency regulation, but is easier to be build and has
enough accuracy for the purpose. The idea is when certain
weight has been filled in the bag, main control module to
reduce motor revolutions, that way making fine dosing and
achieving needed total bag weight precision. Of course,
frequency motor regulation can be added, but this reflects
on the price of GDC-701, especially when three phase asynchronous
motor is used. Base motor is one phase asynchronous with
nominal power 1,1kW/1400n-1. When ordered, this can be different
or frequency control can be added.
Weight measuring module is receiving signal from load cell
to determine current weight of the bag. This load cell is
crucial to be mounted on the right position. With period
of 400ms this module sends information to the main module
and according to that information motor revolutions are
controlled. Other commands are also implemented for correct
machine work. Load cell with sensitivity of 2 mV/V or 3
mV/V can be mounted.
Main module interface to the user is LCD screen 4x40 and
4-button keyboard for interaction and set-up. Several main
parameters for the dosing process can (and must) be defined
- first weight, final weight, motor revolutions when first
weight is present (in percents full motor power), motor
revolutions between first and total weight (again in percents
full power), time when bag's weight is checked, permissible
tolerance of total weight, cycles count, after that 'zero'
command to weight module must take place. Total of 12 presets
can be memorized, can be more when ordered or needed. In
the moment main module can read weight measurement data
up to 3000 divisions and 500gr division value max.(look
EN 45501:2001). Additional option is to send dosing data
to personal computer through serial RS-232/RS-485 interface.
There are also two really outputs - alarm and dose end signals.