Ballast Calculation - ABB SA/S 12.16.6.1 Product Manual

®
ABB i-bus KNX
2.7

Ballast calculation

(150 μs)
Max. peak inrush current I
p
(250 μs)
Max. peak inrush current I
p
Max. peak inrush current I (600 μs)
p
Device technology
The electronic ballast is a device for operating gas discharge lamps, e.g.
fluorescent lamps. During normal operation, it converts the mains voltage to
an optimum operating voltage for the gas discharge lamps. Furthermore, the
electronic ballast enables the gas discharge lamps to ignite (start) via
capacitor circuitry.
With the original choke/starter circuitry the lamps switch on consecutively,
with the electronic ballast all fluorescent lamps switch on practically
simultaneously. If switch on occurs at the mains voltage peak, the buffer
capacitor of the electronic ballast cause a high but very short current pulse.
When using several ballasts on the same circuit, the simultaneous charging
of the capacitors may result in very large system inrush currents.
This peak inrush current I
contacts as well as by the selection of the respective circuit protection. In the
following, the effects of the electronic ballast peak inrush current and the
associated limitation of the number of electronic ballasts on the SA/S are
examined.
The inrush current of the electronic ballast depends not only on the wattage
but also on the type, the number of elements (lamps) and on the
manufacturer. For this reason, the given maximum number of connectible
electronic ballasts per output can only relate to a defined type of electronic
ballast. For a different ballast type, this value can only represent an
estimation.
In order to properly estimate the number of electronic ballasts, the peak
inrush current I with the respective pulse width of the electronic ballast must
p
be known. These values should be stated by the manufacturer in the
technical data or are available on request by now.
Typical values for single element electronic ballasts with T5/T8 lamps are:
Peak inrush current 15...50 A with a pulse time of 120...200 μs.
The relays of the Switch Actuators have the following maximum starting
values:
SA/S 4.6.1 SA/S 2.10.1
SA/S 8.6.1 SA/S 4.10.1
SA/S 12.6.1 SA/S 8.10.1
SA/S 12.10.1
200 A 400 A
160 A 320 A
100 A 200 A
*) x = 5 or 6, C-Load types with and without load current detection
Caution
Do not exceed the threshold values.
Exceeding the value leads to destruction of the relay,
e.g. due to welding.
is to be considered when designing the switch
p
SA/S 2.16.1 SA/S 2.16.5.1
SA/S 4.16.1 SA/S 4.16.5.1
SA/S 8.16.1 SA/S 8.16.5.1
SA/S 12.16.1 SA/S 12.16.5.1
400 A 600 A
320 A 480 A
200 A 300 A
SA/S 2.16.6.1
SA/S 4.16.6.1
SA/S 8.16.6.1
SA/S 12.16.6.1
600 A
480 A
300 A
SA/S | 2CDC 505 056 D0207 35