Rockwell Automation Low-Voltage Switchgear and Controlgear - Manual (Page 6)

2.3.4.4 Current limiting protective equipment ................................................................... 2-11
2.3.4.5 Coordination of electrical equipment .................................................................... 2-12
2.3.4.5.1 Coordination in respect of the switching capacity of the contactor
(overcurrent selectivity)......................................................................................... 2-12
2.3.4.5.2 Coordination with respect to the operability after a short-circuit ........................... 2-13
2.3.4.6 Short-circuit switching capacity............................................................................. 2-14
2.3.4.6.1 Rated short-circuit making capacity I
cm
................................................................. 2-14
2.3.4.6.2 Rated short-circuit breaking capacity I
cu
and I
cs
.................................................... 2-14
2.3.5 Thermal protection................................................................................................ 2-15
2.3.5.1 Ambient temperature ............................................................................................ 2-15
2.3.5.2 Operational overcurrents, heavy-duty starting ...................................................... 2-15
2.3.6 Life span ............................................................................................................... 2-16
2.3.6.1 Prospective service life ......................................................................................... 2-17
2.3.6.2 Mechanical life span ............................................................................................. 2-17
2.3.6.3 Electrical life span................................................................................................. 2-17
2.3.7 Intermittent and short-time duty, permissible frequency of operation ................... 2-20
2.3.7.1 Intermittent duty and relative ON-time .................................................................. 2-22
2.3.8 Rated frequency and harmonics ........................................................................... 2-24
2.3.9 Safety clearances ................................................................................................. 2-24
2.3.10 Mounting position.................................................................................................. 2-25
2.3.11 Protective separation ............................................................................................ 2-25
2.3.12 Site altitude ........................................................................................................... 2-26
2.3.13 Shock and vibration .............................................................................................. 2-26
2.4 Specific application conditions and switching tasks...................................... 2-27
2.4.1 Parallel and series connection of poles ................................................................ 2-27
2.4.1.1 Parallelling ............................................................................................................ 2-27
2.4.1.2 Series connection ................................................................................................. 2-27
2.4.2 AC switchgear in DC applications......................................................................... 2-28
2.4.3 Applications at supply frequencies < 50 Hz and > 60 Hz. Effect of harmonics.... 2-29
2.4.3.1 Effect of the supply frequency on the thermal load............................................... 2-29
2.4.3.2 Effect of the supply frequency on the switching capacity ..................................... 2-31
2.4.3.3 Performance of release units at supply frequencies < 50 Hz and > 60 Hz ........... 2-32
2.4.3.4 Switchgear used with soft starters ........................................................................ 2-32
2.4.3.5 Switchgear for use with frequency converters (inverters) ..................................... 2-33
2.4.4 Application of four-pole switchgear devices.......................................................... 2-35
2.4.4.1 Applications of switchgear with 4 NO contacts ..................................................... 2-35
2.4.4.2 Applications of switchgear with 2 NO and 2 NC contacts ..................................... 2-36
2.4.4.3 Applications of switchgear with 3 NO and 1 NC contact....................................... 2-37
2.4.5 Application of circuit breakers in IT networks ....................................................... 2-37
2.4.6 Switchgear for safety applications ........................................................................ 2-38
2.4.6.1 Mechanically linked contacts ................................................................................ 2-38
2.4.6.2 Mirror Contacts ..................................................................................................... 2-39
2.4.7 Installations in hazardous atmospheres ............................................................... 2-40
2.4.7.1 History, guidelines and regulations....................................................................... 2-40
2.4.7.2 Classification of hazardous areas ......................................................................... 2-41
2.4.7.3 Motors for hazardous areas .................................................................................. 2-43
2.4.7.4 Protection of motors of ignition protection type Increased Safety “e” ................... 2-45
2.4.7.5 ATEX 100a (Directive 94/9/EC) ............................................................................ 2-46
2.4.7.6 IECEx and other approval schemes for hazardous areas .................................... 2-47
LVSAM-WP001A-EN-P - April 2009 0-6