10
During ramp-up, as the SCR firing angle advances, the bus capacitor
is charged by a succession of current pulses. The peak value of these
pulses depends upon the dc bus capacitance, the ramp rate, and the total
inductance, i.e. the sum of the ac line inductance and dc smoothing
inductance, (if present), in series with the bus capacitor.
The inductance needed to limit the normal peak operating current at
full bus voltage will typically also limit the peak current during ramp-up
to an acceptable level. Typically, the source inductance of the line voltage
will be sufficient for this purpose.
Table 3 shows typical maximum peak values of the current pulses
during ramp-up, for various values of bus capacitance and line inductance,
based on the assumption that there is no dc smoothing inductance.
Compatible values of full load dc current are shown. These line inductance
values correspond to an ac source reactance of about 2%, i.e. the voltage
across each line inductance at full current is about 2% of the line to neutral
voltage at 50Hz.
8 . Schematics and Bill of Material.
Schematics and Bill of Materials for the IR1110 Reference Design are shown on
the following pages.
