SIEB & MEYER CNC 0610510, Hardware Description

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Electric Performance Dimensioning
Performance Dimensioning 93
11 Electric Performance Dimensioning
Experience shows that questions arise during the dimensioning of a drive when se-
lecting output stages and power supplies. This chapter shall make clear the physical
background and shall help to dimension correctly the electronic components.
11.1 Components
11.1.1 Output Stage
The output stage of a servo amplifier is specified by the following details:
Voltage range
The maximum intermediate circuit voltage is limited by the used transistors and ca-
pacitors and the minimum space between the strip conductors.
When an output stage with a maximum admissible intermediate circuit voltage of
325 V
DC
(class C) is used, i.e. with an AC power supply of 230 V
AC
, the components
will have a dielectric strength of 600 V
DC
. The reserve is necessary in order to pre-
vent damages in the case of voltage peaks and the intermediate circuit voltages dur-
ing the deceleration.
Current range
The current range specifies the maximum admissible currents. Distinction is made
between peak and rated current:
X The peak current is only admissible for a short time (mostly 5 seconds) and de-
pends on the used transistors and their number.
X The rated current can be provided continuously by the output stage. Its value
depends on the cooling of the transistors, that means: the capacity of the used
heat sink and its ventilation.
11.1.2 Power Supply
The power supply is specified by the following details:
Voltage range
The maximum supply voltage is limited by the used transistors, diodes, and capaci-
tors and the minimum space between the strip conductors.
Current range
The current range specifies the maximum admissible currents. Distinction is made
between peak and rated current:
X The peak current is only admissible for a short time (mostly 1 second) and de-
pends on the used diodes and their number.
X The rated current can be provided continuously by the power supply unit. Its
value depends on the cooling of the diodes, that means: the capacity of the used
heat sink and its ventilation.