HEIDENHAIN MANUALPLUS 620 - 3.29 CML 110 Capacitor Module

292 HEIDENHAIN Technical Manual MANUALplus 620
3.29 CML 110 Capacitor Module
The CML 110 (Capacitor Module Low Voltage) can be used to realize the LIFT-
OFF function if line power fails.
The LIFTOFF function can protect workpieces and tools from damage. When
a power failure occurs and the LIFT OFF function is active, the MANUALplus
620 tries to lift the tool off of the contour, using the residual energy of the DC-
link. In this case, the various enablings for operating the control system must
be maintained during the LIFTOFF. The CML 110 ensures the 24 V supply for
this.
Connection The CML 110 capacitor module is connected via X1 parallel to the 24 V power
supply (++/- -).
The two ++ and - - terminals of the CML 110 are each connected to each other
internally. This makes it possible to connect several CMLs 110 in parallel with-
out needing to use additional external terminals.
Utilizability Calculating the utilizability of the CML 110:
A successful LIFTOFF mainly depends on sufficient energy being available in
the DC-link of the inverter system. Generally it suffices if the energy in the DC-
link is available for the duration of one second. The 24 V supply must also be
ensured for precisely this time. The following formula can be used to check
this:
where:
t = time until U
C
is reached
R
L
= ohmic load of the consumers
C = capacitance of the CML (for CML 110 = 8.3 F)
ln = natural logarithm
U
O
= output load of the power supply unit with which the CML is operated
U
C
= lowest voltage at which the consumers still fulfill their function
Example:
During operation at 24 V, a total current of 10 A is required for switching the
control components on. This corresponds to an ohmic load of 2.4 ohms. In
addition, the voltage for the 24 V components may not sink below 18 V (e.g.
switching voltage of the contactors), for example.
This means:
t = 2.4 Ohm x 8.3 F x ln(24 V/18 V)
t = 5.73 s
If the line voltage fails, then in the best case the voltage will not fall below 18 V
until 5.73 seconds have passed. This is significantly longer than 1 second, and
so the CML 110 is suitable for LIFTOFF here.
Danger
Before service or maintenance work, you must ensure that the CML 110
has been completely discharged.
t = R
L
x C x In (U
O
/U
C
)