* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Motor - Schneider Electric
Electrical ballast wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Power inverter wikipedia , lookup
Electrical substation wikipedia , lookup
Opto-isolator wikipedia , lookup
History of electric power transmission wikipedia , lookup
Pulse-width modulation wikipedia , lookup
Current source wikipedia , lookup
Power engineering wikipedia , lookup
Electrification wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Commutator (electric) wikipedia , lookup
Power electronics wikipedia , lookup
Stray voltage wikipedia , lookup
Buck converter wikipedia , lookup
Surge protector wikipedia , lookup
Three-phase electric power wikipedia , lookup
Mains electricity wikipedia , lookup
Brushless DC electric motor wikipedia , lookup
Distribution management system wikipedia , lookup
Alternating current wikipedia , lookup
Voltage optimisation wikipedia , lookup
Dynamometer wikipedia , lookup
Electric machine wikipedia , lookup
Rectiverter wikipedia , lookup
Electric motor wikipedia , lookup
Brushed DC electric motor wikipedia , lookup
Induction motor wikipedia , lookup
Which MV motor starter to choose? E&S - Tony Narusevicius - 20-09-2005 - English 1 Network starter Motor Load The MV starter and motor are the links between the electrical network and the mechanical load E&S - Tony Narusevicius - 20-09-2005 - English 2 Network The motor starter must be designed to limit the constraints to the network, the motor and the load Protection Motor Load Overcurrent Thermal (I²t) rotor Thermal (Pt100) stator The type of motor starter will influence the perturbations on the network the mechanical strength to the mechanical load the starting torque on the shaft The protection will protect the motor E&S - Tony Narusevicius - 20-09-2005 - English 3 The network has constraints Acceptable inrush current Acceptable starting undervoltage Acceptable power factor short circuit withstand Acceptable harmonics E&S - Tony Narusevicius - 20-09-2005 - English 4 The load has constraints Resistant torque curve Starting inertia Acceptable mechanical stress operating conditions Starting time number of starts automatic starting operating cycle overload locked rotor current deceleration control ........ E&S - Tony Narusevicius - 20-09-2005 - English 5 The motor-starter must be designed to control, protect and supervise the motor for maintenance Motor control: local or remote; automation.... Electrical motor protection short circuit under-voltage ........ Preventive protection temperature through thermal image or sensors bearing vibration sensors moisture derating for altitude ......... The design of the motor starter should decrease the number of spare parts.... ......... E&S - Tony Narusevicius - 20-09-2005 - English 6 The most common motor: asynchronous motor phase 2 phase 3 phase 1 the 3 windings of the stator are placed at 120° and are fed by the service voltage these 3 coils create a rotating magnetic field around the axis of the stator this magnetic field creates a current in the rotor the rotation of the rotor N is lightly slower as the magnetic field one Ns 120° E&S - Tony Narusevicius - 20-09-2005 - English There are 2 types of asynchronous motors single or double cage motors (rotor is short circuited) slip ring rotor motor (resistance of the rotor can be modified by introducing external resistances) 7 Influence of the service voltage on the motor torque Torque V"s > V's V's >Vs starting torque Vs acceleration torque Ns N (speed) The lower the voltage; the lower the motor torque If the motor torque is lower than the resistant torque the motor does not start E&S - Tony Narusevicius - 20-09-2005 - English 8 Asynchronous motor single cage rotor double cage deep slot rotor motor starting torque low from 0.6 to 1 Tr slightly higher from 0.8 to 1.2 Tr maximum torque around 2 to 2.2 Tr around 2 to 2.2 Tr (slightly higher for deep slots) from 4.5 to 5.5 Ir from 5 to 6.5 Ir starting current excellent mechanical and electrical robustness simplicity of design no brushes relatively low power factor 0.8 to 0.9 on full load if asynchronous installed motor power is high reactive, power compensation may be required these motors are ideal for intensive use and hazardous environments E&S - Tony Narusevicius - 20-09-2005 - English 9 Asynchronous slip ring rotor motor the impedance of the rotor winding can be modified by introducing external resistances. by decreasing external resistance on starting (from Rr" to R), the characteristic of the torque is translated and the starting torque adapted to the torque of the machine. T Rr ’' > Rr ’ > R= rotor resistance T max Ts T load N E&S - Tony Narusevicius - 20-09-2005 - English 1 0 Synchronous motor The main differences with asynchronous motors are: their constant speed (synchronous speed) the rotor circuit supplied with Dc the power factor which may be set by the exciting current In a conventional synchronous motor controller the DC power is applied from an external source brushes and slip rings carry the current to the field winding A brushless synchronous motor it generates its own DC power for its field the amount of DC power is controlled through induction low current DC power applied from the controller E&S - Tony Narusevicius - 20-09-2005 - English 1 1 Load torque curves of machines compressor E&S - Tony Narusevicius - 20-09-2005 - English 1 2 Starting conditions: motor torque must always be greater than the load torque the motor does not start the motor starts running point E&S - Tony Narusevicius - 20-09-2005 - English 1 3 Some of the different types of MV motor starter Full voltage on the stator or direct on line FVNR or DOL Reduced Voltage through reactance Reduced Voltage through auto-transformer RVAT Reduced Voltage trough soft starter RVSS (SoftStart) E&S - Tony Narusevicius - 20-09-2005 - English 1 4 Network Direct stator starting on full voltage (FVNR) Protection Motor Load Locked rotor current on starting is around 4 to 7 In depending on motor characteristics starting time of 1 to 10 seconds depending on the moment of total inertia (motor + machine), motor torque and load torque the network must be able to withstand the starting current without disturbing other loads the machine being driven must be able to withstand the mechanical impact due to the motor torque This mode is very popular (simple, robust, not expensive) E&S - Tony Narusevicius - 20-09-2005 - English 1 5 Network Reduced voltage by reactance L1 Protection Motor Load This starting mode reduces current inrush on the network in the simplest manner. Since the motor starting torque is low, the machines being driven must have a relatively low torque during star up: compressors; centrifugal pumps; converter sets.... T/Tn T L1shunted Id/In I Tmax I L1shunted 4 T with L1 2 I with L1 2 Tr 1 If(Tr) In resistant torque N N1 Nn E&S - Tony Narusevicius - 20-09-2005 - English N N1 Nn 1 6 Reduced voltage by auto-transformer Ct1 Network Motor Load Ct2 Protection Ct3 This system is recommended for high power motors. It has the advantage of not dissipating energy. It can be used to obtain, for the same decrease in current, less reduction in torque than with the reactor starter. Id/In T/Tn I Tmax 4 2 2 Tr 1 If(Tr) In resistant torque N N N1 N1 Nn E&S - Tony Narusevicius - 20-09-2005 - English N1 Nn 1 7 Auto Transformer starting Sequence First stage: CT1 must be closed before CT2. CT1 and CT2 are closed CT3 is open Second stage: First stage : the motor is starting with reduced voltage. CT1 is opened CT2 CT2 remains closed Third stage: Second stage: the motor is running in series with part of the autotransformer winding. CT3 remains open CT3 is closed CT3 CT2 CT2 remains closed CT1 remains open CT1 CT3 The motor is always supplied during the second stage, when CT1 is open. Third stage: the motor runs at full voltage. CT2 M CT1 CT3 CT1 is opened CT2 are andclosed CT3 are closed CT2 M CT1 M E&S - Tony Narusevicius - 20-09-2005 - English 1 8 Network Reduced voltage by Soft Starter Protection Soft starter Motor Load The soft starter is an solid state device which controls the starting period of the motor depending on the application several settings are possible. When the motor is running a contactor shunts the electronic starting module. Advantages Reduction of starting current Reduction of starting torque and mechanical shock ( the torque may be adjusted to the resistant torque) smooth acceleration and deceleration of the motor It is a solution when auto-transformer motor starter is not possible. But it is not a variable speed starter Only the price limits the use of the Soft Starter E&S - Tony Narusevicius - 20-09-2005 - English 1 9 Soft starter setting: different possibilities current limitation setting torque control setting mix of both ........ deceleration possibilities E&S - Tony Narusevicius - 20-09-2005 - English 2 0 Network Soft starter setting: current limitation Soft starter Protection Motor Load The voltage is increased until the starting current reaches the limit, then voltage is maintained at this current, and then the voltage is increased again up to the service voltage fix frequency T/Tn T=function Tmax 2 ( ) U Un Is/In I and Torque limited T= Tn * (In / Il)2 4 2 Il 2 Tr 1 Limit of the starting current Tsn In If(Tr) Tlimited resistant torque N N1 Nn E&S - Tony Narusevicius - 20-09-2005 - English N N1 Nn 2 1 Network Soft starter setting: torque control Soft starter Protection Motor Load The voltage is set to have a motor torque just above the resistant torque. If the resistant torque is constant the starting voltage may be close the full voltage; the inrush current maybe close the direct on line inrush current I and T N and CT torque control speed ramp fonction of torque ramp x In I starter U starter=> F I1 Un In Tn U1 T1 Nn Tn resistant torque T1 = k.I1 F1 E&S - Tony Narusevicius - 20-09-2005 - English t t1 resistant torque t t1 2 2 Network Soft starter: normal setting Protection Soft starter Motor Load The initial torque setting applies sufficient voltage to the motor to cause the motor shaft to begin to turn. This voltage is gradually increased overtime (as per the ramp time setting) until either: the motor accelerates to full speed the ramp time expires a current limit is reached. If the motor has not reached the full speed at the end of the ramp setting, the current limit setting will proportionally control the maximum output torque The current remains limited for as long it takes the motor to accelerate to full speed. When the motor reaches full speed and the current drops to running level, the by pass contactor shunts the soft starter module.The motor is now running at the full voltage. E&S - Tony Narusevicius - 20-09-2005 - English 2 3 Network Soft starter setting: deceleration Protection Soft starter Motor Load The starter may be used to control the deceleration by slowly reducing the voltage to the motor upon initiating a stop command the most common application for the decel feature is pumping application, in which a controlled stop prevents water hammer and mechanical damage to the system. E&S - Tony Narusevicius - 20-09-2005 - English 2 4 Starting mode selection table application Permanent or quasi permanent process<1/day Frequent starts>1/day Starting mode Machines requiring high start torque Motor with low current inrush or low power Pumps fans, Machines starting compressors, with low torque frequent starts 1 Circuit breaker or 1 contactor Direct On Line / Full voltage 1 contactor Simplicity, less investment On starting: High torque High current inrush High mechanical stress Reduction of current in rush on starting Poor power factor Stator by reactance Optimisation When starting Stator by of starting current must be autotransformer characteristics reduced, but the necessary starting or soft starter torque maintained Optimisation of high torque The most difficult rotor starting starts characteristics E&S - Tony Narusevicius - 20-09-2005 - English Controlled Advantages by disadvantages 3 contactors Optimisation of torque and current inrush on starting 2 contactors expensive generally 3 contactors Small current inrush and high starting torque 2 5 Starting mode selection table yes - deceleration control ? - the drive between motor and load is able to withstand the mechanical stress of a direct on line start no no yes - constant torque with high starting torque as crushers, grinders, mixers ...... yes no Network requirement - accepts full starting current? - accepts starting voltage drop? -accepts the starting reactive consumption power? no Investment Increase yes no yes no yes - accepts the current oscillation during an open transition? yes VSD specific no yes - accepts the harmonics during the starting period no yes FVNR E&S - Tony Narusevicius - 20-09-2005 - English no RVAT RVSS 2 6 main protection overload overcurrent, thermal image, and thermal sensors short circuits To protect the motor and the network fuses and instantaneous over-current relay bearing overload temperature simulated by relay thermocople RTD faults give rise to: increased current in the stator earth leakage protection (differential protection) vital to comply with the worker protection protection windings and magnetic circuit zero sequence current relay under-voltage: common protection, prevents the motor on working on overload over-voltage: fluctuations on the network prevents long motor starting and over temperature speed or current thermal protection Incomplete phase, phase reversal and unbalance insulation fault in the winding stator/ frame under and over voltage incomplete starting or frequent starts locked rotor under power or undercurrent other protection E&S - Tony Narusevicius - 20-09-2005 - English protection of the motor against thermal damage mainly for pumps specified by motor manufacturers 2 7 Rating Current of the contactor The power of a motor is the mechanical power. To determine the rating of the contactor we have to calculate the full load current of the motor. The electrical power of the motor will be the mechanical one divided by the efficiency. Is= Pm/(Us x V3 cosj *h) where Pm: power of the motor Us service voltage cosj power factor h efficiency of the motor Ir contactor > Is * k (k derating factor) if the altitude <1000m k=1 E&S - Tony Narusevicius - 20-09-2005 - English Altitude (ft) Voltage Current 3300 (1000 m) and below 5000 (1500 m) 10,000 (3000 m) 1.00 0.95 0.80 1.00 0.99 0.96 2 8 What do you think? For an asynchronous motor, true false the highest starting torque is supplied by the Full Voltage Motor starter the higher the voltage, the higher the starting torque with a full voltage motor starter the network capability to accept the inrush current needs to be verified the inrush current may generate a voltage drop at the terminals of the motor the distance between the motor starter and the motor has no influence on motor starting motor starting through an auto-transformer is always a cycle of three steps it is possible to continuously operate an auto transformer motor starter on an intermediate step the auto transformer motor starter may be used for every application the auto transformer is generally designed in accordance with the motor use for each project different starting configurations are available in the soft starters Soft starters use an electronic device to reduce the voltage Soft starters maybe used to adapt the running speed Soft starter maybe used to control the deceleration soft starter needs 2 contactors with a soft starter it is possible to adjust the starting torque to the resistant torque E&S - Tony Narusevicius - 20-09-2005 - English 2 9 Do you agree? For an asynchronous motor, true false the highest starting torque is supplied by the Full Voltage Motor starter the higher the voltage, the higher the starting torque with a full voltage motor starter the network capability to accept the inrush current needs to be verified the inrush current may generate a voltage drop at the terminals of the motor the distance between the motor starter and the motor has no influence on motor starting motor starting through an auto-transformer is always a cycle of three steps it is possible to continuously operate an auto transformer motor starter on an intermediate step the auto transformer motor starter may be used for every application the auto transformer is generally designed in accordance with the motor use for each project different starting configurations are available in the soft starters Soft starters use an electronic device to reduce the voltage Soft starters maybe used to adapt the running speed Soft starter maybe used to control the deceleration soft starter needs 2 contactors with a soft starter it is possible to adjust the starting torque to the resistant torque for some application the soft starter may create inrush current similar to the full voltage motor starter E&S - Tony Narusevicius - 20-09-2005 - English 3 0