Siemens Standard Drives Application Handbook

1 Siemens Standard DrivesApplication HandbookMartin BrownSiemens Standard DrivesCongleton December 199721. What is a Variable Speed Drive?.. The Variable Frequency Siemens Standard Drives Product Product Selecting a Overall Supply Side Motor Load Acceleration and Braking Environmental Installing and Getting Started with an Mounting the Wiring up the First Switch If the motor does not Some Simple Applications and Using a Potentiometer with the Analog Using a Digital Using the Fixed Using other digital input Using the control Current Limit and Protection Other Protection Some Additional Electromagnetic Compatibility (EMC).. What is EMC?.. Minimising the problem of EMC Rules and Some Real A simple Fan A Closed Loop Controller using a Controlling Lift Door A Lift system for Industrial A Conveyer Application using several A Material Handling An Industrial Washing An Exercise Machine Advanced Applications Using Closed Loop Braking and Slowing down using Using the Serial Using Vector and FCC Options for Siemens Standard Clear Text Operating Panel Braking Modules and Braking RFI Suppression PROFIBUS Input and Output APPENDIX 1: Using the USS Hardware Overview of the USS Message Detailed Description of the USS Protocol Examples of using the USS APPENDIX 2: Environmental Protection Levels (IP rating).

2 8812. APPENDIX 3: Some Useful manual is intended to help users of variable speed Drives successfully installand utilise Siemens Standard includes an introduction to Drives , which may be informative to first time users. Advanced information is shown in italics, and may be skipped on first technical information and complete parameter descriptions areavailable in the What is a Variable Speed Drive?A Variable Speed Drive (VSD) consists of a Motor and some form of electric VSDs consisted of AC and DC motors combinations which wereused as rotating controllers. The first electronic controllers used Thyristor (SCR)Rectifiers which controlled the voltage, and therefore the speed of DC DC VSDs are still widely used and offer very sophisticated , the DC motor is large, expensive and requires periodic brushmaintenance. The AC induction motor is simple, low cost, reliable and widelyused throughout the order to control the speed of an AC induction motor a more complex controller,usually called an inverter is required.

3 In order to understand how an inverter works, it is necessary to understand howan induction motor induction motor works like a transformer. When the stator (the fixed, outerwinding) is connected to a three phase power source, a magnetic field whichrotates at the frequency of the supply is set 13213 Simplifed Induction Motor - Cross SectionStator WindingsAir GapRotor ShaftThis field crosses the air gap between the stator and rotor and causes currentsto flow in the rotor windings. This produces a force on the rotor as the currentinteracts with the changing magnetic field, and the rotor the windings are arranged in several pairs (or poles), the frequency of therotating field will be less than the applied frequency ( two pole = 50/60Hz =3000/3600rpm, but four pole = 50/60Hz = 1500/1800 rpm).However, if the rotor runs at the same speed as the rotating field, there will be nochanging magnetic field, and therefore no torque.

4 Therefore the rotor always runsa little slower than the rotating field in order to generate torque. This difference inspeed is known as OperatingPointTorque Speed Characteristic of An Induction MotorSlipPull out (Maximum) TorqueTorqueVariable frequency operationHence the speed of the motor depends on the applied frequency, as well as thewinding arrangement, and a little on the in order to control the motor speed it is necessary to control thefrequency of the the frequency is reduced, the voltage must be reduced or the magnetic flux willbe too high and the motor will saturate. Hence the voltage must be controlled aswell. If the frequency is increased above normal, more voltage would normally beneeded to maintain maximum flux; this is not usually possible, so less torque isavailable at high , VoltageSpeed ( X 50/60)Torque Reduction above Base speedTorque CapabilityTherefore in order to control the speed of a Standard AC motor, the appliedfrequency and voltage must be it is difficult to control voltage and frequencies at these high powers, theuse of a Standard induction motor allows a cost effective speed control system tobe The Variable Frequency electronic converter which converts Direct Current (DC) to Alternating Current(AC) is known as an inverter.

5 Electronic speed controllers for AC motors usuallyconvert the AC supply to DC using a rectifier, and then convert it back to avariable frequency, variable voltage AC supply using an inverter bridge. Theconnection between the rectifier and inverter is called the DC link. The blockdiagram of a speed controller (often called an inverter) is shown below:8 RectiferDC Link InverterSupply C+-CInverter Block DiagramThe supply, which can be single phase (usually at low power) or three phase isfed to a full wave rectifier which supplies the DC link capacitors . The capacitorsreduce the voltage ripple (especially on single phase supplies) and supplyenergy for short mains breaks. The voltage on the capacitors is uncontrolled anddepends on the peak AC supply DC voltage is converted back to AC using Pulse Width Modulation (PWM).The desired waveform is built up by switching the output transistors (InsulatedGate Bipolar Transistors; IGBTs) on and off at a fixed frequency (the switchingfrequency).

6 By varying the on and off time of the IGBTs the desired current canbe generated, but the output voltage is still a series of square wave pulses. PulseWidth Modulation is shown in the figure Width ModulationVoltageCurrentThere are many complex aspects of inverters which need to be consideredduring the design:9 The control system to calculate the PWM requirements is very complex andspecially designed integrated circuits (ASICs) are needed. The control electronics are often connected to the DC link, which isconnected to the supply, so the customer connections, display etc. must besafely isolated from this. The output current must be carefully monitored to protect the inverter andthe motor during overload and short circuit. At first switch on the DC link capacitors are discharged, and the inrushcurrent must be limited, usually using a resistor which is bypassed by arelay after a few seconds. All connections to the inverter, especially the supply and controlconnections, may carry a lot of interference and must be fitted with suitableprotection components.

7 An internal power supply with several different output voltages is needed forthe to supply the control electronics. The inverter, especially the IGBTs and rectifier diodes, produce heat whichmust be dissipated using a fan and heatsink. The PWM output voltage contains many high frequency harmonics(because of the fast switching) and can be a major source of EMI. The input rectifier draws current only at the peak of the supply waveform, sothe input currents have a poor form factor ( the RMS value can be quitehigh - this does not mean the inverter is inefficient!)A practical inverter needs to be designed for ease of use and installation. Largeinverters are often specially designed or engineered for each Application ;smaller inverters are designed for general purpose use and are of standarddesign. Siemens Standard Drives division manufacture Standard inverters up to90kW for this Siemens Standard Drives Product current product range consists of four different product types:The MICROMASTER Vector.

8 A VSD high performance inverter for generalpurpose applications available in various voltage ranges and power up MICROMASTER. A similar range with fewer features for MIDIMASTER Vector. A higher power version of the MICROMASTERV ector with output capability of up to COMBIMASTER. An induction motor with an inverter mounted in place ofthe terminal following information refers to the operation of the MICRO andMIDIMASTER Vector products, but may prove useful with reference toCOMBIMASTER as Product RangeThe details of the MICROMASTER Vector product range are shown below. Thepower range available varies from 120W (MMV12) to (MMV750) :1/3 AC 230V +/- 15% (187-265V). 1 AC 230V +/- 15% (187-265V) with integrated RFI FIlterTypePowerWidthHeightDepthSizeMMV12 -75, MMV12/2-75/2120-750W73147141 AMMV110-150,MMV110/2-150/21,1-1,5kW14918 4172 BMMV220-300,MMV220/2-300/22,2 -3,0kW185215195 CMMV400/2 4,0kW185215195C3AC 380-500V +/- 10% (342-550V)TypePowerWidthHeightDepthSizeM MV37/3-150/3,0,37-1,5kW73147141 AMMV220/3 - 300/22,2 -3,0kW149184172 BMMV400/3 - MMV750/34,0kW -7,5kW185215195 CThe same power range and voltage variants are available with reducedperformance; types MM12 etc.

9 The are known as the Standard , orMICORMASTER Basic MIDIMASTER is available in four different frame sizes and three differentvoltage ranges. Power ratings up to 90kW Variable Torque (see Section )are AC 400-500V +/- 10% IP21/NEMA1 TypePower CT/VTFrame SizeMDV750 AC 230V +/- 10% IP21/NEMA1 TypePower CT/VTFrame SizeMDV550 SizeWidthHeightDepth42754502005275550202 62756502787420850310575V units and IP56 units are also details of the product range are available in catalogue following information refers to the MICROMASTER and MIDIMASTERV ector products. Some features may not be available on basic MICROMASTERor COMBIMASTER Selecting a drive selection is straight forward, as a motor is already installed and thespeed range requirement is not excessive. However, when a drive system isselected from first principles, careful consideration may avoid problems ininstallation and operation, and may also save significant Overall Check the Current rating of the inverter and the motor.

10 Power rating is only arough guide. Check that you have selected the correct operating voltage. 230V three phaseinput MICROMASTERs will operate with single or three phase inputs; 400 VMICROMASTERs are for three phase Application only. Single phase inputunits can be more cost effective in some cases, but note that 230V units willbe damaged if operated at 400V. See section MIDIMASTERs will operate with three phase only, and are available for 230V,400V or 575V supplies. Check the speed range you require. Operation above normal supplyfrequency (50 or 60Hz) is usually only possible at reduced power. Operationat low frequency and high torque can cause the motor to overheat due to lackof cooling. Synchronous motors require de-rating, typically by 2-3 times. This is becausethe power factor, and hence the current, can be very high at low frequency. Check overload performance. The inverter will limit current to 150 or 200 % offull current very quickly - a Standard , fixed speed motor will tolerate theseoverloads.