Page 509 - Motor_protection_and_control_Manual_motor_starters_ contactors

Lighting circuit switching

Contactor selection

General
Contactor selection criteria for control of lighting circuits are as follows:
– type, power rating and number of lamps
– connection mode
– current values on closing and in steady state
– power factor
– presence or not of correction capacitors.

Lighting circuits
In a given circuit, the number and power rating of lamps are defined and cannot result in overload. Only short-circuit protection
has to be provided. gG fuses or modular circuit-breakers will be chosen for this purpose.
The lamps have very specific technical data, according to their construction type.
– Incandescent lamps have a very high current on closing: more than 15 times nominal current. 5
They do not introduce a large phase displacement between current and voltage
– Fluorescent tubes are equipped with a ballast whose purpose is two-fold: contribute to ignition and limit current to nominal
value once steady state is reached. This ballast is a reactor that considerably lowers the power factor. It may or may not be
compensated.

Individual compensation Serial compensation in dual mounting
(parallel compensation)
S S

S

Selection of contactors
The following tables indicate, for each contactor type, the maximum permissible number of lamps per phase. Air temperature,
near the contactor, must be limited to 60 °C. Numbers are given for a 230 V voltage distributed between phase and neutral:
single-phase (phase + neutral) or three-phase (3 phases + neutral) distribution, lamps are wired in star connection. In the case
of a three-phase supply without neutral, 230 V phase-to-phase, the permissible number of lamps per phase will be that given in
the tables multiplied by 0.58.

Example:
120 x 100 W / 230 V incandescent lamps - 400 V three-phase network with distributed neutral.
Calculate the number of lamps per phase: 120 : 3 = 40. On the 100 W line of the incandescent lamp table, contactor AF09 is
limited to 38 lamps per phase, you must thus select contactor AF12 which accepts up to 43 lamps per phase.

1SBC101961S0201 - Rev. B

ABB | 5/309