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UTILIZATION CATEGORIES FOR
LOW VOLTAGE SWITCHGEAR AND CONTROL GEAR
A
B
DC-1
DC-3
DC-5
DC-6
DC-12
DC-13
DC-14
DC-20
DC-21
DC-22
DC-23
AC-1
AC-2
AC-3
AC-4
AC-5a
AC-5b
AC-6a
AC-6b
AC-7a
AC-7b
AC-8a
AC-8b
AC-12
AC-13
AC-14
AC-15
AC-20
AC-21
AC-22
AC-23
AC
AC
and
DC
DC
947-4
947-5
947-3
947-2
947-4
Relevant I.E.C.
Product Standard
947-3
947-5
1) By plugging is understood stopping or reversing the motor rapidly by reversing motor primary connections
while the motor is running.
2) By inching (jogging) is understood energizing a motor once or repeatedly for short periods to obtain small
movements of the drive mechanism
Typical Applications
Category
Nature of
Current
PAGE 207
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Non-inductive or slightly inductive Loads, resistance furnaces
Slip-ring motors: Starting, switching off.
Squirrel-cage motors: Starting, switching off motors during
running.
Squirrel-cage motors: Starting, plugging
1
), inching
2)
Switching of electric discharge lamp control
Switching of incandescent lamps.
Switching of transformers
Switching of capacitor banks.
Slightly inductive loads in household appliances and similar
applications.
Motor-loads for household applications.
Hermetic refrigerant compressor motor control with manual
resetting of overload releases.
Hermetic refrigerant compressor motor control with automatic
resetting of overload releases.
Control of resistive loads and solid state loads with isolation
by optocouplers.
Control of solid state loads with transformer isolation.
Control of small electromagnetic loads.
Control of A.C. electromagnetic loads.
Connecting and disconnecting under no-load conditions,
Switching of resistive loads, including moderate overloads.
Switching of mixed resistive and inductive loads, including
moderate overloads.
Switching of motor loads or other highly inductive loads.
Protection of circuits, with no rated short time withstand current
Protection of circuits, with a rated short time withstand current
Non-inductive or slightly inductive Loads, resistance furnaces
Shunt-motors, Starting, plugging
1
), inching
2)
, dynamic breaking
of motors.
Series-motors, Starting, plugging
1
), inching
2)
, dynamic breaking
of motors.
Switching of incandescent lamps.
Control of resistive loads and solid state loads with isolation by
optocouplers.
Control of DC electromagnets
Control of DC electromagnetic loads having economy resistors
in circuit.
Connecting and disconnecting under no-load conditions
Switching of resistive loads, including moderate overloads.
Switching of mixed resistive and inductive loads, including
moderate overloads (e.g. shunt motors)
Switching of highly inductive loads (e.g. series motors).