Siemens 7XT3300-0 A00/DD Series Manual page 8

English
Auxiliary Voltage Supply
The auxiliary voltage of the 7XT33 can be supplied either by a 3-phase current or by the
direct voltage of a station battery. For a commissioning test, which is limited in time, the
7XT33 can also be powered by a single-phase alternating voltage.
Function of the 20-Hz Generator
The 7XT33 provides a rectangular output voltage with a frequency of 20 Hz. The voltage
r.m.s. value is 25 V under load.
The binary input (terminal points 6, 8) can be used to block the 20-Hz generator. The
blocking function via the binary input is activated, once the input signal has been provided
for 500 ms. Afterwards, the output module is switched off, the red LED (ERROR) lights up
and the "Life contact" relay drops out (idle state).
The device features the following monitoring functions:
When the auxiliary voltage is switched on or the device is restarted, an auxiliary voltage
threshold of approx. 80 V must be exceeded before the 20-Hz output signal is generated
and the "Life contact" relay picks up. Within this time, the green LED (RUN) is flashing.
The blocking function via the binary input is not active during this time.
If the internal device voltage drops due to an external short-circuit (e.g., between the
7XT33 and the 7XT34) or an inadmissible output overload, the 7XT33 will be protected
by turning off the output module. The "Life contact" relay drops out (idle state) and the
ERROR LED lights up. After a delay of approx. 60 s, the device attempts to restart. The
ERROR LED keeps flashing during the restart. If the fault has not been eliminated, the
ERROR LED lights up and the device attempts to restart after a delay. This procedure is
repeated until the fault is eliminated. If the internal device voltage is provided again, the
device restarts automatically.
If the 20-Hz output voltage is lower than 17 V, e.g., in the event of a short-circuit, or higher
than 73 V under operating conditions (internal device voltage within the permissible
range), the output module is switched off, the "Life contact" relay drops out and the
ERROR LED lights up. An overvoltage of more than 73 V might be an interference
voltage on the generator side.
8
Note
If the 3-phase current supply is implemented by connection to a 3-
phase voltage transformer, please make sure that the transformer is
powerful enough. Recommendation: more than 100 VA.
7XT3300-0*A00/DD
C53000-B119U-C129-1