w240 pf700 vc sugar centrifuge lab1

Break-Out Session Name: Engineering Assistant Tools

Lab Developer: Josh Olive, Roman Lichon

Lab Exercise: Lab 1 – Sugar Centrifuge Application

Engineering Assistant – Tools

Lab 1 – Sugar Centrifuge Application

Table of Contents

BACKGROUND........................................................................................................................... 2

LAB OBJECTIVES............................................................................................................................ 2CONVENTIONS USED IN THIS LAB....................................................................................................2EQUIPMENT LIST............................................................................................................................ 2LAB SETUP.................................................................................................................................... 3

SECTION 1: SUGAR CENTRIFUGE APPLICATION..................................................................4

MACHINE DESCRIPTION.................................................................................................................. 4MACHINE CYCLE............................................................................................................................ 4GIVEN INFORMATION...................................................................................................................... 5OBJECTIVEL................................................................................................................................... 5USE AVAILABLE TOOLS...................................................................................................................5Solution........................................................................................................................................ 9

Conventions Used in This Lab

ATTENTION: Identifies information about practices or circumstances that can lead to personal injury or death, property damage or economic loss. Attention statements help you identify a hazard, avoid a hazard, and recognize the consequences.

TIP: Identifies information that is helpful, but not necessary, in completing a task.

FYI: Provides additional information regarding the lab equipment, but is not needed to complete the lab.

Background

Engineering Assistant is a software tool offered, by the Commercial Engineering Group with Allen-Bradley Standard Drives Business, as an aid and guide to analyzing process applications by providing general tools for unit conversions, electrical power formulas, inertia and power calculations, and specific application calculator tools that prompt specific input necessary to size drives and motors.

Lab Objectives

This lab is designed to familiarize the student with sizing a drive/motor for a centrifuge application using the Centrifuge Calculator offered within Engineering Assistant.

Equipment List

(1) PC with the latest Engineering Assistant software.

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Lab Setup

1. Study the application scenario described for what information and what unit of measurement is provided.

2. Outline a method organizing what is needed to achieve the goals of the Lab.

3. Choose the appropriate tools from Engineering Assistant that can assist your effort.

4. Graph visual results

5. Save and retrieve Results.

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1.

Section 1: Sugar Centrifuge Application

Machine Description: This machine is used to reduce moisture content prior to additional processing. The centrifuge works by spinning the sugar slurry (massecuite made from either sugar cane or sugar beets) at a high speed. The centrifugal force pushes the slurry to the side, forcing liquid through perforations in the basket while solids are retained inside. The basket consists of a fine screen or cloth. The basket resides inside the centrifuge, close to the centrifuge wall. The remaining solids (cake) can then be washed and spun at higher C’s to achieve a relatively dry cake. The resultant cake is then discharged through the bottom of the basket by means of a single motion plow like mechanism.

Machine Cycle: 1. Accelerate to a low speed and fill the centrifuge with the slurry.2. After loaded, accelerate to full speed (also called spinning/centrifugal speed).3. Decelerate to a minimum speed to unload. At this point the remaining sugar is scraped out of

the centrifuge’s basket.Total typical cycle time is 3 minutes, which equates to 20 cycles per hour minimum.

Speed Profile

0

200

400

600

800

1000

1200

0 10 20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

Time (sec)

RP

M

Spinning (Centrifuging)

Filling

Unloading

1445 kgm2

700 kgm2

1150 kgm2

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Given Information:Motor:

Power: 330 kW Base Speed: 888 RPMEfficiency: 95.5 % Current: 535ATorque: 3581 NmVoltage: 460VBase Freq: 60 Hz

Machine:Cycles per hour: 22Inertia empty: 700 kgm2Inertia full: 1445 kgm2Inertia after spinning: 1150 kgm2Fill speed: 180-200 RPMFill time: 15 SecAccel time to top speed: 40 SecSpinning (Centrifuge) Speed: 1100 RPMSpinning (Centrifuge) Time: 35 SecDecel time from Spinning Speed to Unload Speed: 33 SecUnload Speed: 50 RPMUnload Time: 40 Sec (includes Accel Time to Loading Speed)

Objective: Determine drive size and dynamic braking requirements. Offer an effective solution.

Use Available Tools:

Use the Centrifuge Calculation Tool to calculate torque and power requirement. Based on formula:

where M is in Nm, and J is in kgm2

TIP: Open the Centrifuge Calculator tool with in Engineering Assistant to determine what is needed and units of measure to work with. Also explore other tools that may help working with the data given or missing.

__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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Try converting the given data to be entered into the calculator tool, without just copying the values shown. The following screen views are for confirmation, that you understand the data you are entering.

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TIP: Note that if you did not use the given information to calculate the Initial Accel Time correctly and subtract it from the T6 Unload time, the tool warns that 22 cycles cannot occur within the time period. So adjustments need to be made.

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Solution: Perform checks for peak torques and peak currents. Note that peak torque demanded

happens to be regeneration torque at 1100 RPM in the constant HP range is 133.44 %. This may be okay, since most motors are designed to at least generate 200% torque for a short time at rated speed. This application duration for that level of demand is relatively short compared to the entire cycle, should be feasible to operate at, but requires due diligence to verify that the motor design spec sheet supports the demand with room to spare.

Graph the Results. What becomes visually noticeable during the cycle? _________________________________________________________________________________

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Note that the equipment will be operating at 3822 Nm / 3581 Nm = 107% (2819 lbft / 2641 lbft = 107% from Results Tab) of motor torque for about 33 seconds out of the entire cycle. Will the motor be able to handle this? Probably. But, if necessary, we could extend the decel time from 33 to 36 seconds and shave off some time somewhere else. Looking at motor data could be very important to make this decision.

Now that the motor is sized okay, the 535 Amp rating of the motor and the graph , should help determine the drive to specify. (But not necessary for this Lab)

By nature, centrifuges have a significant percent and duration of its cycle regenerating energy. This makes regenerating energy back onto the power source much more feasible and justifiable. So this tool promotes a solution based on the present 1336R for dynamic braking.

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Even if the 1336R was not to be chosen, the results provide peak torque and current information that can be used to size other dynamic braking hardware solutions.

Try to Save and then retrieve the file by accessing File in the upper left corner of the tool. This allows for several variation studies to be done and to be able to come back and continue at a later date. Note that printing results can also be done to facilitate communication.

Design Limitation Insight: Using (3) 1336Rs in regen brake mode in parallel. This can only be done in regen brake

mode. Based on testing, we can’t get much overload out of 1336Rs in this mode without possibility of tripping on overcurrent. Common mode reactors are used to help reduce peak currents on AC line from regen brakes.

Whenever designing or specifying more than one 1336R unit per dynamic braking application, consult with the factory about special precautions.

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STOP HERE. This is the end of the lab.

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