Datasheet

23
Useful information
Categories of duty - as per IEC 947 / IS 13947
Current Utilisation Typical Application
Categories
AC AC1 Non-inductive or slightly inductive loads, resistance furnances
AC2 Slipring motors; starting, switching off
AC3 Squirrel-cage motors; starting, switching off motors during running
(1)
AC4 Squirrel-cage motors; starting, plugging, inching
AC5a Switching of electric discharge lamp controls
AC5b Switching of incandescent lamps
AC6a Switching of transformers
AC6b Switching of capacitor banks
AC7a Slightly inductive loads in household appliances and similar applications
AC7b Motorloads for household applications
AC8a Hermetic refrigerant compressor motor
(2)
control with manual resetting of overload releases
AC8b Hermetic refrigerant compressor motor
(2)
control with automatic resetting of overload releases
DC DC1 Non-inductive or slightly inductive loads, resistance furnaces
DC3 Shunt-motors: starting, plugging, inching, dynamic braking of d.c motors
DC5 Series-motors: starting, plugging, inching, dynamic braking of d.c motors
DC6 Switching of incandescent lamps
(1) AC3 category may be used for occasional inching (jogging) or plugging for limited time periods such as machine set-up; during such limited time periods the
number of such operations should not exceed five per minute or more than ten in a 10-min period.
(2) Hermetic refrigent compressor motor is a combination consisting of a compressor and a motor, both of which are enclosed in the same housing, with no
external shaft or shaft seals, the motor operating in the refrigent
(3) Selection of contactors for utilisation categories from AC-5a to AC-8b and DC6 upon enquiry.
Contact life calculation:
Contactors have bounce free operation. Electrical life is influenced
by the breaking currents. For normal AC3 duty the breaking
current is the rated operational current and for AC4 duty, the
typical breaking current is 6 times the rated operational current. In
case of mixed duty, the expected life is determined as under
Where
X = expected life for mixed duty
A = expected life for normal AC3 duty
B = expected life for 100% AC4 duty
C = proportion of inching operations as a percentage of total
operations.
Recommended selection of contactors for hoisting duty (upto 85A)
In hoisting operation, slipring motors are generally used. For this typical hoisting duty, we recommend the contactors listed in the following
table.
Contactor Stator Protection Rotor Protection Max rotor
Type Maximum load current with hoisting motor. Maximum load current with hoisting motor(Delta circuit). standstill
For intermittent duty S3 For intermittent duty S3 voltage
25% 40% 60% 100% 25% 40% 60% 100%
AAAAAAAA V
3TF31 10 10 9 8 15 14 13 12 660
3TF33 17 16 15 13 25 24 22 20 660
3TF45 28 25 23 20 42 38 35 30 660
3TF47 49 45 40 30 73 68 60 45 750
3TF49 68 62 54 45 100 95 80 68 1000