Rockwell Automation Low-Voltage Switchgear and Controlgear - Manual (Page 117)

Function Current-measuring Temperature-measuring
Bimetal Electronic PTC sensor Linear sensor
Protection against
overload and
overtemperature in
continuous duty
X X X X
Protection against
overload and
overtemperature
under special (e.g.
obstructed) cooling
conditions
--- --- X X
Protection against
overload / overtem-
perature during
starting
X
incl. rotor-critical
machines
X
incl. rotor-critical
machines
X
excluding rotor-
critical and
thermally very
fast-reacting
machines
X
excluding rotor-
critical and
thermally very
fast-reacting
machines
Protection at
intermittent service
(X)
depending on the
operating cycles
X
relays with
switching-over to
cooling time
constants
X
excluding rotor-
critical and
thermally very
fast-reacting
machines
X
excluding rotor-
critical and
thermally very
fast-reacting
machines
Stalling
protection
(X)
via thermal
protection
X
undelayed
(X)
via thermal
protection
(X)
via thermal
protection
Starting-time
monitoring
(X)
via thermal
protection
X
(X)
via temperature
(X)
via temperature
Underload prot. --- X --- ---
Ground fault prot.
1)
--- X --- ---
Short-circuit prot.
1)
--- X --- ---
Phase-loss
protection X
accelerated
X
short delay
X
via temperature
X
via temperature
Asymmetry
protection
--- X
(X)
via temperature
(X)
via temperature
Temperature-rise
display
--- X --- X
Warning before
tripping
--- X
(X)
with 2. set of
sensors
X
Display time to trip --- X --- ---
Start interlocking --- X
(X)
with additional set
of sensors
X
Current monitoring --- X --- ---
Protection of
EExe motors
X X X X
Control switching-
over Y-D
--- X --- ---
Communication --- X --- X
Settings Current All parameters ---
Response
temperature(s)
Tab. 4.1-4
Summary of functions of protective relays with focus on motor protection
X
available (possibly as option)
(X) limited or restricted availability
--- unavailable
1)
Disconnection via circuit breaker
The listed functions are discussed in more detail below.
LVSAM-WP001A-EN-P - April 2009 4-9