Control Devices for Metering and Batching Equipment

SD-01 Control System

SD-01 control system within a continuous belt batcher is aimed at providing volumemetric and gravimetric batching of continuous flow of bulk materials as per setup metrological parameters.

Operation Features

Metering materials at the dumping section of batching conveyor
Metering irregular distribution of the belt linear density
Adjustment of material weighing when the length of belt changes
Manual and automatic correction of discharge as per humidity and content of the materials
Material batching as a continuous flow and as preset batch

Basic Parameters for SD-01 Control System

Permissible error when metering material weight, out of the maximum weighing limit, %	±0.1
Limits of permissible error for batchers as per maximum performance provided that the batcher operates continuously for at least 6 minutes, %	±0.5
Supply voltage of monophase alternate current with frequency 50±0,5 , V	from 187 to 242
Performance limits, t/h	from 1.6 to 999999
Power demand, W, not more	50
Ambient temperature, ºС	from -10 to +35
Dust-proof-and-moisture-proof class of the cabinet (as requested)	IP54 (IP65)

SD-01 Supports the Following Batching Modes

Volume metric - continuous batching basing on preset value of nominal rate of the conveyor belt
Gravimetric - continuous batching basing on preset nominal rate of the batcher performance
Batching - discharging a preset portion of materials in volume metric or gravimetric modes selected by the user

SD-01 Functionality

When controlled by the upper level (automatic mode) PCS, SD-01 control system for material supply provides the following:

Receipt of instructions for start and cancellation of discharging, switching batcher operation modes (volume metric, gravimetric and batching), system restart
Receipt and setup of material dose, preset and general capacity, rate of the batcher belt

SD-01 generates current data on the status of conveyor actuator, feeder and bin agitator (readiness and operation state), current capacity values, linear density and belt rate and forwards them to the upper level , also it generates data on current belt length, archive data reports on discharging for previous and current hours, shifts and days (up to 20 days).

Exchanging data with the upper level of SD-01 through standard Modbus RTU protocol.

When operating in manual mode SD-01 can provide the following functions from control panel:

Operations on setting up instructions, discharge parameters setup and display, the same as for automatic operation mode
Setting up weighing parameters, belt length, maximum belt rate, variable belt density
Setting up process PID control parameters for conveyor motor, capacity limits, interface for data exchange with the upper level of PCS, agitator operation, limits of permissible conveyor belt slip
Calculation of current weight of materials through processing signals from strain sensors
Calculation of current rate and monitoring of belt slip through processing frequency signals from sensors of rotation for drive shaft and output shaft of the transporter
Executing instructions to start, stop, setup and blocking operations through digital outputs
Controlling the agitator and belt movement through digital signals on readiness, start and operation state of the agitator and conveyor drive
Controlling belt rate through analogue control current signal (4-20 mA) to the conveyor drive
Defining belt positioning on drums through signals from position sensors
Digital display of the state through digital signals Operation of the agitator and conveyor drive, SD-01 being ready to operate with the upper level, emergency situations
Calculation of current capacity basing on collected current data on material weight and belt rate

Hardware Functions

SD-01 provides receipt and processing signals with the following parameters:

Feature	Acceptable value
Feature	Min	Nom	Max
Strain Measuring Channel for Weight Metering
Quantity, ea.	-	-	2
Load resistance (from 1 to 4 sensors connected in parallel), Ohm	95	380	-
Output voltage for sensor feeding, V	±5.7	±6.0	±6.3
Digital Input
Quantity, ea.	-	-	19
- logical zero level, V	0	-	6
- logical one level, V	12	-	30
Duration of input signal, ms	50	-	-
Digital Output
Quantity, ea.	-	-	8
Commutating voltage, V	8	-	30
Current load, A	-	-	0.2
Analogue Output
Quantity, ea.	-	-	2
Current, mA	4	-	20
Frequency Signal Input
Quantity, ea.	-	-	2
- logical zero level, V	0	-	4
- logical one level, V	8	-	30
Ranges of measured frequency, Hz	1	-	10000

Design

SD-01 is designed as a cabinet with equipment located inside or as a panel to be installed to the cabinet (implemented solution - SKUD cabinet with three panels SD-01 and three BZP-08 units for parameter setup located on the door with control devices).

The following equipment is located to cabinet panel: control devices for batcher mode, BZP-08 unit for parameter input and displaying batching state.

Depending on the Customer's requirements, control system for batching can vary, and it will be reflected in the relevant design documents.

Batcher Control Principle

Control principle for continuous belt batcher is based on performance calculation P at the specific time moment:

where Q - linear density of material on the belt at the specific time moment
V - belt rate at the specific time moment

In gravimetric batching mode the capacity set up by the user will be provided and supported.

Depending on the material linear density variations there could be deviations in current capacity from preset value. In order to support the preset value the rate of belt is to be adjusted.

In volume metric batching mode regular belt rate is supported and weight of the discharged material G(t) is calculated as per the following formula:

where G(t) is weight of discharged material
             Р(t) - current capacity
             t     - current time
           Δt   - time of discharge

SD-01 Schematic Block Diagram

Components of SD-01