a new contactor range from abbdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · a new...

50
ABB Control SECRL - 1 2001-06-19 A New A New Contactor Contactor Range from ABB Range from ABB New Generation ABB Contactors

Upload: others

Post on 18-Aug-2020

11 views

Category:

Documents


2 download

TRANSCRIPT

Page 1: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 1 2001-06-19

A New A New Contactor Contactor Range from ABBRange from ABBNew Generation ABB Contactors

Page 2: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 2 2001-06-19

The ABB range of A contactorsThe ABB range of A The ABB range of A contactorscontactors

A 9, A 12, A 16 A 26, A 30, A 40 A 50, A 63, A 75 A 95, A 110

A145, A185 A210, A260, A300 AF400, AF460 AF580, AF750

New Generation ABB Contactors

Page 3: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 3 2001-06-19

Customer

Final product

ü Questionnaireü Interviewsü Analysisü Feedback/ follow-up

ABB

QFD - Quality Function Deployment• a systematic way to ensure that the customers’ needs are met• customers are involved throughout the whole process

New range developed from customer requirementsNew range developed from customer requirementsNew Generation ABB Contactors

Page 4: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 4 2001-06-19

D System components/co-ordination

D1 Critical dimensionsD2 Co-ordination with other system components

E User friendliness

E1 Personal safetyE2 Easy to installE3 Easy maintenanceE4 Aesthetic designE5 Low noise level

Blue bar is customers preferenceGreen bar is the rating of EH range

Example of QFD - AnalysisExample of QFD - AnalysisExample of QFD - AnalysisNew Generation ABB Contactors

Page 5: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 5 2001-06-19

Participating customersParticipating customersAirCond Carrier, TraneComp Atlas Copco, Kaeser, Ingersoll Rand Crane LiebherrDrive ABB Strömberg Industry, RobiconGenset Elcat, Tranudis, ExideLift Kone, OTIS, Schindler ElevatorPump Grundfos, Weir, Firetrol, HubbelWind Micon

RockWool, Holmegaards glaesverker, Wisa Forest, Saugbrugsforeningen, Brunvoll, Union, Korsnäs, STORA Billerud

ABB Installation Neutral, Schubert, Demas, ABB Electric, Circuit Electric, DanControl, ABB FIDIS, Vahva Sähkö,Nuova Esi, George Kontoulis, ABB Distribusjon, Storm Elektro, UME, ABB Installation, Delta Electrical Systems, GEC, S&I, Kontex ABB Gebäudetechnik, Cegelec, TCS, ABB Installasjon, Rolls Royce IPG

OEM

Industry

Panel Builders

New Generation ABB Contactors

Page 6: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 6 2001-06-19

ABB ABB contactorscontactors

• ABB-line - a system concept• Easy to install• Safe and simple to work with• Improved performance• A comprehensive range of accessories• ABB offer

New Generation ABB Contactors

Page 7: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 7 2001-06-19

New design of large contactors New design of large New design of large contactorscontactors

• Terminals at the same levelas other system components

• Contactor fits perfectly withABB breakers, switch fusesand overload relays

New Generation ABB Contactors

Page 8: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 8 2001-06-19

ABB ABB contactors contactors - a compact range- a compact range

• The most compact contactorrange on the market

• Low built-in depth (no safetyclearance needed to door)

• Built-in terminals

New Generation ABB Contactors

Page 9: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 9 2001-06-19

Complete system co-ordinationComplete system co-ordinationComplete system co-ordination

• Contactors

• Breakers

• Switch fuses

• Electronicoverload relays

• Thermaloverload relays

ABB-line - a system concept

Page 10: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 10 2001-06-19

Co-ordination contactors - Isomax breakersCo-ordination Co-ordination contactorscontactors - - IsomaxIsomax breakers breakers

In lineSide by side

ABB-line - a system concept

Page 11: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 11 2001-06-19

Co-ordination Co-ordination contactors contactors - - Isomax Isomax breakersbreakers

Breaker S3/S4 S5 S6 S7

Contactor A145-A185 A210-A300 AF400-AF580 AF750

ABB-line - a system concept

Page 12: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 12 2001-06-19

A complete motor starter solutionA complete motor starter solution

MCCB with built-in advanced motorprotection (SACE PR212/MP)

• Trips contactor at– Overload– Phase loss or unbalance– Locked Rotor

• Trips breaker at short circuit

ABB-line - a system concept

Page 13: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 13 2001-06-19

Co-ordination contactors - switch fuses/overload relaysCo-ordination Co-ordination contactorscontactors - switch fuses/overload relays - switch fuses/overload relays

Contactor - switch fuse Contactor - electronic overload relay

ABB-line - a system concept

Page 14: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 14 2001-06-19

ABB system provides savingsABB system provides savings

• Installation time

• Installation material

• Panel space

ABB-line - a system concept

Page 15: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 15 2001-06-19

Easy access to auxiliary circuitsEasy access to auxiliary circuitsEasy to install

Front access to auxiliarycircuits facilitates cabling

Page 16: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 16 2001-06-19

Clear indications on frontClear indications on front

All technical data clearlymarked on the front

Easy to install

Page 17: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 17 2001-06-19

Snap-on accessoriesSnap-on accessoriesSnap-on accessories

• Snap-on surge suppressors

• Snap-on auxiliary blocks

Easy to install

Page 18: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 18 2001-06-19

Inserts-holder to facilitate cablingInserts-holder to facilitate cabling

3-pole device to hold inserts inplace while tightening the bolts

Easy to install

Page 19: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 19 2001-06-19

A focus on safetyA focus on safetyA focus on safety

• Touch safe - IP 20 fromfront

• Unintentional manualoperation prevented

• Clear visual indication ofstatus

• High safety even withoutoptional shrouds

Safe and simple to work with

Page 20: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 20 2001-06-19

Safe and easy inspection of contactsSafe and easy inspection of contactsSafe and easy inspection of contacts

Operation of the contactoris impossible whileinspecting the contacts

Safe and simple to work with

Page 21: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 21 2001-06-19

Easy to change coil on installed contactorEasy to change coil on installed Easy to change coil on installed contactorcontactor

No need to removepower cables

Safe and simple to work with

Page 22: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 22 2001-06-19

Coil interface (AF Coil interface (AF contactorscontactors))

A new technology integrated into a ”traditional” contactor!

Improved performance

Page 23: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 23 2001-06-19

~=

Transistor

Coil

Rectifier

Integratedcircuit

Electronic coil Electronic coil controlcontrolImproved performance

• Always DC current over the coil

• Controlled current levels at pull-in

and holding

• Integrated circuit developed by ABB

Page 24: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 24 2001-06-19

• Sensibility to voltage variations– Chattering contactors– Welding– Humming contactors

• A wide variety of coils needed to cover customerneeds

• High energy consumption• Voltage transients at opening

Coil interfaceCoil interface

The solution to problems such as:

Improved performance

Page 25: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 25 2001-06-19

Distinct opening and closingDistinct opening and closing

Contactorclosed

Contactoropen

100 V 250 V

Controlvoltage

Position

Nominal range

Accepted range

77% of lowervoltage range level

55% of lowervoltage range level

Improved performance

Page 26: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 26 2001-06-19

Improved performance

Coil voltages (AFCoil voltages (AF contactors contactors))

Coil codes AF145-AF75020… 60VDC 72 (For AF145-AF300)24… 60VDC 68 (For AF400-AF750)48… 130VAC/DC 69100… 250VAC/DC 70200… 500VAC/DC 71

AF145-AF300 20-60VDC 48-130VAC/DC 100-250VAC/DC 200-500VAC/DC

AF400-AF750 24-60VDC 48-130VAC/DC 100-250VAC/DC 200-500VAC/DC

Page 27: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 27 2001-06-19

Reduced energy consumptionReduced energy consumptionImproved performance

• At holding, the current through the coil is minimised• Energy consumption reduced by 65%

~=

Transistor

Coil

Rectifier

Integratedcircuit

Page 28: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 28 2001-06-19

• Conventional contactors cause a voltagepeak at opening which may harmsurrounding electronic equipment

• Using a coil interface reduces the voltagepeak considerably since the energy isconsumed in a controlled way

No voltage transient at openingNo voltage transient at opening

~=

Transistor

Coil

Rectifier

Integratedcircuit

I

Improved performance

Page 29: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 29 2001-06-19

Low voltage signal Low voltage signal controlcontrol

AF400-AF750 can be controlledwith low voltage signals (24VDC), i.e. directly from a PLC

Improved performance

Page 30: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 30 2001-06-19

- 24V +

ON

OFF_N

COMMON

On

Off

Supply VoltageVoltageMatningssp

A1 A2

Improved performance

Low voltage signal Low voltage signal controlcontrol

Page 31: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 31 2001-06-19

Coil interfaceCoil interface

• Standard on AF400-AF750

• Option on A50-A300

Improved performance

Page 32: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 32 2001-06-19

A wide range of accessoriesA wide range of accessories

ABB offers a wide range of accessories tofacilitate installation and use of our

contactors

A comprehensive range of accessories

Page 33: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 33 2001-06-19

Wide range of accessoriesWide range of accessoriesWide range of accessories

• Electronic overload relays

• Thermal overload relays

• Auxiliary contact block

• Mechanical interlock(Horizontally mounted contactors)

• Mechanical interlock(vertically mounted contactors)

• Surge suppressor, type RC

A comprehensive range of accessories

Page 34: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 34 2001-06-19

Wide range of accessoriesWide range of accessoriesWide range of accessories

• Cable connector for Cu cables• Cable connector for Al and Cu cables• Terminal shrouds• Double connector• Connection sets for Y-D and reversing

starters• Terminal extensions• Adapter plate for easy changeover from

EH range

A comprehensive range of accessories

Page 35: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 35 2001-06-19

Contact blocksContact blocks

• Snap-on for easy mounting• The same block fits the

whole range• Up to 4 contact blocks per

contactor• Wiping function improves

performance

A comprehensive range of accessories

Page 36: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 36 2001-06-19

Connection set for Y-D starterConnection set for Y-D starter

• Completely protected connections• IP20 from front

A comprehensive range of accessories

Page 37: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 37 2001-06-19

Connection set for reversing starterConnection set for reversing starter

A comprehensive range of accessories

Page 38: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 38 2001-06-19

Cable connectorsCable connectors

Double connector

Single connector forCu cables

A comprehensive range of accessories

Page 39: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 39 2001-06-19

Terminal shroudsTerminal shroudsEasy-to-fit terminalshrouds for connectorsand compression lugs

A comprehensive range of accessories

Page 40: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 40 2001-06-19

Mechanical interlockMechanical interlock

• Vertical• Horisontal

A comprehensive range of accessories

Page 41: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 41 2001-06-19

Terminal enlargementTerminal enlargementA comprehensive range of accessories

Page 42: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 42 2001-06-19

Conversion EH to A-rangeConversion EH to A-rangeConversion EH to A-range

Adapter plate available foreasier changeover from EHrange to new large A-range

A comprehensive range of accessories

Page 43: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 43 2001-06-19

ABB OfferABB OfferThe ABB offer

• Documentation

• Quality and environment

• Certificates and approvals

• World wide presence

Page 44: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 44 2001-06-19

DocumentationDocumentation

• Complete co-ordinationtables elaborated throughextensive testing

The ABB offer

Page 45: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 45 2001-06-19

Co-ordination tables availableCo-ordination tables availableCo-ordination tables available

• 400 V MCCB Isomax up to 50kA

• 500 V and 690 V MCCB Super limiting Isomax upto 50kA

• 400 V and 690 V Fuses aM and gG up to 80kA

• 415 V BS Fuses

• 480 V MCP and MCCB Isomax up to 85kA (UL)

• 600 V MCP and MCCB Isomax up to 35kA (UL)

• 600 V Fuses up to 80kA (UL)

The ABB offer

Page 46: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 46 2001-06-19

Dimension drawings available on fileDimension drawings available on fileDimension drawings available on file(PDF, DWG and DXF format)

The ABB offer

Page 47: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 47 2001-06-19

Quality and environmentQuality and environment

All products madein ISO9001 and ISO14001certified factories

The ABB offer

Page 48: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 48 2001-06-19

Reduced environmental impactReduced environmental impactReduced environmental impact

• Easy recycling - no combinedmaterial (metal and plastic)

• Low LCA index thanks to choice ofmaterial (in contacts and plastic)

• Cadmium and silicone free

• No ozone depleting halogens

The ABB offer

Page 49: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 49 2001-06-19

Certifications and ApprovalsCertifications and ApprovalsThe ABB offer

Page 50: A New Contactor Range from ABBdjang.co.kr/download/abb/1_3_1.pdf · 2016. 10. 28. · A New Contactor Range from ABB New Generation ABB Contactors. ABB Control SECRL - 2 2001-06-19

ABB ControlSECRL - 50 2001-06-19

ABB - a world wide supplierABB - a world wide supplier

ABB is represented inover 140 countries

The ABB offer