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SYNCHRONOUS MOTOR DRIVES
The VHJ Ltd. has developed special microprocessor
controlled exciter units for the excitation and start of synchronous motors
and generators.
At start, the controller of the exciter unit ensures by inserting a resistance
into the rotor circuit, that the synchronous machine can start as an asynchronous
motor, then by giving appropriate excitation it makes the machine jump
into synchronism. Corresponding to the operation mode, it can be set that
the control be effective by a constant exciting current or constant power
factor (cosφ) or constant reactive power.
Depending on the way of cooling, the grade of protection
is IP21 in case of ventilated execution and it is IP54 in case of closed
execution. In the latter case, the heat transfer between the external
and internal air is ensured by a heat exchanger (air conditioner).
The flexible fitting to the technological environment is made possible
by I/O modules of appropriate number and type on the hardware side and
by the program of the freely programmable PLC of the controller unit on
the software side. For the connection to an intelligent device, RS232
port is at the user's disposal in the basic execution. As options a CAN
bus or an RS422 connection are available.
A large display mounted on the house, an intelligent internal log facility,
a waveform storing device and selective error signaling routines make
easier the maintaining of the operation and the troubleshooting of the
drives.
The program and the interface cards make possible that installing the
drive in almost every technological environment, the necessary control
(of current, voltage, revolution per minute, position, pulling force,
field weakening) and the reception respectively the generation of all
necessary technological signals can be realized without any additional
hardware.
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