LS Industrial Systems - Total Solution Provider : MCCB, MC, INVERTER, PLC

Variable Frequency Drive / Inverter

	Starvert series is one of leading variable frequency drive(AC drive). Basic function of AC drive is to transform DC to AC electronically and controls the speed of motor by changing voltage and frequency inputted from common power(AC220V/440V). Starvert series offers wide lineup to satisfy various industrial-needs. With LS Starvert series, you can be benefited from energy-effective and environment-friendly automation system.

Overview

Application

Line-up

iC5

iG5

iG5A

iS5

iP5A

iS7

iV5

Switchover

Textile(Loom)

Introduction

- Driving of yarn drum of loom should be controlled in line with main motor. Because the conventional system uses reduction gear, gearing ratio should be changed if the product type is altered. Therefore, we decided to control tension using inverter.
- Field : Textile/loom
- Type : iS5/iS7

Process configuration

Main function

- Linkage control: Speed of main motor that releases the spool should be controlled in line with line speed of the drum ⇒ Rpm of main motor (for spool driving) is used as feedback for main speed control.
- PID control: Feedback tension control

System configuration

Textile(warper)

Introduction

- Winds several strands of yarns in a plane. Inverter controls winding and tension power.
- Field: Textile/Warper
- Type: SV150iS7-4/SV150iS5-4
- Motor spec: 15㎾,440V.60㎐

Process configuration

Main function

- Winder: Winds aligned yarns
- Bridle Roll: Applies tension to yarns
- Comb-shaped structure: Aligns yarns uniformly

Others

- In the system construction diagram, the threads consist of more than hundreds (300~600) of yarns. Yarns released from the threads are aligned by the comb-shaped structure and tension is applied to them while they pass the bridle roll. Then, they are wound by the winder after passing the second comb-shaped structure .

Operation Method

- The bridle roll controls back tension with vector inverter. The winder is controlled by “PI” using iS7/iS5.

Textile(Traverse)

Introduction

- When winding yarns, it is necessary to guide the yarns with traverse.
- By traverse operation, the drum’s rpm is altered periodically, so that the yarns do not cluster locally (ribbon effect) or cut off.
- Field: Textile machine/loom
- Type: SV-iS5/iS7

Process configuration

Main function

- Traverse operation is performed using traverse function of APP Group, which is characteristic of iS5
- Conventionally, traverse operation was performed using inverter’s up-down operation and FDT function. However, it required additional volume and contact points.

Others

Slitting machine

Introduction

- Slits material of sanitary napkin for women (width: 1 m) in 8 strands and rewinds it.
- Field: Linked controller/unwinder, slitting, rewinder, pinch
- Type :

Unwinder: 037iS7-2 1EA

Slitting bridle: 037iS7-2 1EA

Rewinder: 022iS7-2 4EA

Pinch machine: 037iS5-2 1EA

Process & system configuration

Main function

- Maximum line speed is 200m/m, and 10V main speed control is input.
- Unwinder: Because minimum diameter of roll is 100? and the gearing ratio is 30:46,40:132,30:24, i.e. 4.048:1, the maximum motor speed is (200/0.1π)(132/40)(46/30)(24/30)=2577rpm. Also, because maximum diameter of the initial material is 1500?, motor speed at the maximum line speed becomes (200/1.5π)(132/4046/30)(24/30)=172rpm. That is, 172 ~ 2577 rpm should be maintained at the maximum line speed.
- Slitting bridle: Because minimum diameter of roll is 114? and the gearing ratio is 24:44,21:44, i.e. 3.841:1, the maximum motor speed becomes (200/0.1π)(44/21)(44/24)=2145 rpm.
- Rewinder : Because minimum diameter of roll is 190? and the gearing ratio is 30:46,1:5, i.e. 7.667:1, the maximum motor speed becomes (200/0.1π)(46/30)(5/1)=2569rpm. And, at the maximum diameter of 1200?, the motor speed becomes (200/1.2π)(46/30)(5/1)=407rpm.
- The rewinder uses torque minor loop mode in iV5 winder version.
- The unwinder uses iV5 winder version with variable external PI speed control. The Looper position data is linked with front slitting bridle operation.

Socks making machine

Introduction

- LS inverter used for main driving source of socks manufacturing machine
- Field: Socks manufacturing machine
- Type: Inverter (SV-iG5A)

Process & system configuration

Major function

- Inverter

Forward driving startup (FX-CM)

JOG function

Speed control by keypad

Torque increase by manual torque boost function

Others

- Production speed can be regulated by controlling motor speed with inverter
- Because JOG operation is possible, tangled yarns can be disentangled using JOG frequency.
- Noise is reduced by inverter operation.
- Machine handling becomes easy because machine operating part and inverter can be connected easily.

Steel plate line speed control system

Introduction

- LS inverter used in steel plate production line
- Field: Individual machine (roller)
- Type: SV-iS7

Process configuration

Major function

- Forward driving startup (FX-CM)
- Up/Down operation
- Jog frequency operation
- Use DB resistor
- Motor overheat prevention
- Overload trip

Others

- Leveler’s main role is to remove residual stress.
- Product size can be controlled precisely by leveler line speed control using inverter.
- UP-Down operation and Jog function for ease operation.
- Vector was used to precisely control line speed in order to obtain precise dimension of final product.
- AC reactance was applied at input line for power-factor improvement and input circuit protection.

Coiler driving system

Introduction

- The conventional winding motor requires large current for startup and is disadvantageous in productivity.
- Inverter is used to reduce startup current and improve productivity.
- Load : Coiler
- Inverter: SV1320iP5A-4 (132kw)
- Motor:110㎾ (Modified winding motor)

Process configuration

Major function

- During startup: Acceleration time should be selected so that the normal speed can be attained within 1min for general 150% load.
- During stoppage : Because the rotational inertia is large, free run stoppage and machine brake are used.

Others

- Because winding motor is used directly to inverter, internal resistance of the motor was removed. ⇒ During wire connection, overheat may damage the wire.

Extruder(Screw type)

Introduction

- LS inverter used for extruder screw driving
- Field: Extruder screw
- Type: Inverter (SV-iP5A)

Process & system configuration

Major function

- Inverter

Forward driving startup (FX-CM)

Speed control by variable resistor (V1)

Motor overheat prevention

Overload trip

Others

- Productivity can be increased because extruder screw speed can be easily controlled by variable resistor (V1).
- The screw speed can be controlled in real time depending on the temperature of extruder cylinder.
- If the motor is overloaded or overheated because of poor extrusion, the self-protection function protects the motor and inverter without additional equipment.
- Because the motor speed is controlled by frequency, the wider and more precise control is possible compared with conventional step control.
- Motor noise is reduced.

Running machine

Introduction

- LS inverter used for controller of running machine driving motor
- Field: Running machine
- Type: Inverter (SV-iC5)

Process & system configuration

Major function

- Inverter

Forward driving startup (FX-CM)

Speed change by Up/Down operation

Sensorless vector operation

Motor overheat prevention

Overload trip

Control by communication

Others

- Strong torque characteristics at low speed by sensorless vector
- Smooth acceleration/deceleration and reduced noise
- Product stability increased by motor overheat prevention and inverter overload prevention
- Communication with running machine specific controller is possible

Industrial washing machine

Introduction

- Industrial washing machine : Hotel, Hospital Factory, Laboratory, Chemical, etc
- Field : Machinery(Washing Machine)
- Inverter : SV-iG5A(1phase : 1.5,2.2kW), SV-iS5/iS7(3phase : 5.5,7.5kW)
- Motor : 1Hp ~ 10Hp

Process & system configuration

Major function

- Speed commend : Multi step operation or RS485 : Low speed(washing), high speed(dehydration)
- Acc/dec. time auto transfer : two deferent acc/dec. time ⇒ low speed and high speed
- Overheat level setting feature and overheat trip : When reach to the overheat level, according to the set value ⇒ Decel/stop, Free Run/stop, or lower the carrier frequency to prevent the trip

Others

- 16 level multi step operation16 level multi step operation
- Acc/dec. time auto transfer feature ? only for LGIS

Printing machine

Introduction

- Prints two colors after unwinding paper roll, and then rewinds it.
- Field: Individual machine (printing machine)
- Inverter: SV037iS7-4 (3.7kw)
- Motor spec: 3.7㎾ (Encoder equipped to general motor : 1,000Pulse)

Process & system configuration

Major function

- ASR (Automatic speed regulator) P,I gain control ⇒ P gain : 40% I gain : 400ms

Others

- The rpm variation should be within 1rpm for printing accuracy. ⇒ If variation becomes large, printing position may not coincide in 1-color printing and 2-color printing.

Hoist(Lift)

Introduction

- A system for driving hoist, which is used for repairing lighting towers of baseball park. No precise control is required, but it is required to improve riding comfort.
- Field: Hoist/lift
- Type: inverter(SV-iS7)

Process configuration

Major function

1) Speed control by voltage
2) Inverter run output is used for brake signal
3) Lifting/descent signal is controlled by the rider with lever.

Others

1) Dynamic Braking resistor is used to prevent release during deceleration.
2) Acceleration/deceleration time is determined by stop signal and stop position from test operation. DC brake is used to improve riding comfort during brake.
3) Brake opening signal should be generated by accepting inverter run signal because signal delay or signal error may happen, and it is recommended to equip additional protection equipments such as governor in preparation for inverter error.

※ Braking operation system

Elevator

Introduction

- LS vector inverter used for high speed elevator
- Field: Elevator
- Type: Inverter(SV-iV5L)

Process & system configuration

Major function

1) Height detection by inverter
2) Acquires optimum speed pattern by calculating remaining distance
3) Position signal is transferred to main controller continuously
4) Driving signal of electronic brake is directly controlled by inverter

Others

1) iV5-L or iV5 can be selected depending on requirements of main controller.
2) Because the inverter should send and receive specific signal with main controller, matching with the main controller is important.(iV5L Version)
3) Motor characteristic value is tuned without really driving the motor, by stop-type auto-tuning.

AHU control

Introduction

- Damper control → Inverter control ▶ Energy saving / Automatic control
- Facility : AHU(Air handling unit)
- Model: SV-iS7/iS5, iG5A, iP5A

Process & system configuration

Major function

- Create the optimum air control through VFD
- Automatically control the air flow
- Supply is on and return is automatically on or off depending on the flow of air

Control system

Others

- Total VFD no. : 49
- Control 49 VFD through RS485 communication from the main control PC in control room
- VFD automatically control the air flow according to the speed commend from control room

Cooling Tower

Introduction

- Cooling tower is used to cool down circulation water of chemical process. Because the cooling method is air-cooling, fan is required. The fan is driven by motor.
- Conventionally, cooling of circulation water was done in On/OFF mode. However, we introduced speed control by inverter for precise control and energy saving.
- Field: Fan/cooling tower
- Type: iP5A

Process configuration

System configuration

Main function

- Frequency jump: Generally, the cooling tower has two or three resonance points within 0~60㎐. Therefore, operation may happen at resonance points if inverter is used for speed control. In this case, shafts that link motor bearing or motor with fan may be damaged.
⇒ When applying frequency jump function, precise resonance points should be identified. For this purpose, speed is gradually checked in installation.

Aeration tank motor driving system

Introduction

- DO(dissolved Oxygen) of water is controlled for rapid reaction of pollutants and chemicals.
- Inverter is used for speed control.
- Inverter is used for precise control and energy saving.
- Field: Blower/aeration tank
- Type: SV750iP5A-4(75kW)
- Motor spec: 75kW, 2-pole

Process & system configuration

Main function

- PID control is used to precisely control water concentration.

Others

- Even the blower is energy-saving load, energy is not saved if aeration tank is the main load. ⇒ Pressure is applied to the blower of aeration tank because it is positioned in water. Therefore, a large torque is required to overcome the pressure and expel air bubble. Here, the water pressure acts as damper.

Humidity control

Introduction

- Humidity control of textile factory is important with regard to product quality.
- The humidity control is performed by spraying moisture in room between air path. Generally, this spraying is controlled by valve, but if inverter is used, there will be advantage in control efficiency and energy saving.
- Field: Pump
- Type: SV-iP5A

Process & system configuration

Major function

- Because the installed valve control system is replaced by motor speed control system, all that is required is matching valve control amount and speed control output. No additional function is required.

Others

- If there arises current non-equilibrium at input, this is due to factory electricity supply. It can be solved by adding reactors.

Apartment water supply system

Introduction

- Water supplying to apartment households
- Field: Water supply pump for high-rise apartment
- Type: Inverter(SV-iP5A)

Process & system configuration

Major function

- Inverter

Forward driving startup (FX-CM)

Speed control by variable resistor(V1)

Control by communication
- PLC

Process PID control

Others

- PLC (Master-k80s) was used as main controller. Speed of 4 inverters was controlled by PID control.
- Because the water volume is controlled in real time using inverter, the conventional water tank becomes unnecessary.
- Motor noise is reduced remarkably because motor speed is controlled by inverter.
- Remote water supply system control is possible using PMU (optional).

Fuel pump driving system

Introduction

- Fueling pump for supplying oil to airplane. Oil pressure is maintained by inverter depending on load change.
- Field: Pump
- Type: SV-iP5A

Process & system configuration

Major function

- To maintain constant pressure, load (fueling amount) is controlled by inverter in order - PID control
⇒ 4~20mA of pressure signal is transferred to DCS, and DCS sends PID output for inverter control.

Others

- Because the motor was for medium-voltage (6,600V), UP/DOWN transformer was used to control low voltage inverter (440V).
⇒ Inverter input was decreased from 6,600V to 440V. Then, inverter output was increased from 440V to 6,600V because the motor was for 6600V.
⇒ Heat resistance is important when selecting the UP/DOWUN transformer, because heat is generated