Owing to its modular, highly flexible design, full-fledged technology and outstanding degree of safety, this device enables the user to cope with nearly all controlling and monitoring tasks. The controller is provided with a manifold, local I/O system which is selected through an extremely fault-tolerant CAN bus. The modules can be arranged any way in various places and are only connected among one another by a common bus cable, which also facilitates expansion.
Furthermore, two 3-phase measuring systems have been integrated, which enable all system parameters, such as voltage, current, power factor, power, frequency, speed, working hours, etc., to be read directly on the controller and also to be evaluated in the controller.
Additional tasks, such as synchronizing and power-factor control, have been implemented as well, which provide for a reliable parallel operation of a system. In large-scale systems, several controllers can be networked among one another and interchange data through an additional CAN interface. The controller has been developed and tested in accordance with the basic standards for electromagnetic compatibility (EN50081-2 and EN50082-2) and therefore withstands even the most adverse impacts of an industrial environment.
In spite of the complex scope of controlling and measuring tasks, operation is kept simple and clear in order to achieve maximum operator convenience for a Hitzinger system. This aspect is underlined by the integrated measuring system and output on the integrated LCD which represents the central source of information. Of course, there are additional information units, such as a mimic diagram, which essentially facilitates checking the circuit state of a system.
At the front side of the controller-the central information and operating unit-a membrane keyboard insensitive to moisture and dirt is located which serves to control all functions of the system. The mimic diagram is also provided with a touch-sensitive front panel and thus resists the mostly extreme ambient conditions.
With a view to optimum analysis in case of fault, all fault messages and various individually programmed operating messages are recorded in the controller in a failsafe mode so that system faults can be reconstructed more easily and precisely. If the system is equipped with a modem, these records can also be remote-transmitted and evaluated, for example, by our service department.
Functional Description of the Basic Unit
The basic unit can be additionally equipped with two 3-phase measuring systems each for voltage and current or another measuring unit for two 1-phase systems (synchronizing), which also includes two speed inputs and two analog outputs.
If several control systems are to be networked (max. 8), POWERCON can be equipped with an additional CAN bus interface (CAN bus 2).
CAN Bus 2
At the CAN_2 interface, up to eight POWERCONs can be networked among one another and interchange data, for which max.16 messages (full CAN) are available. One message can optionally contain either 64-bit (digital values) or four 16-bit integer variables (analog values). The transmission speed is 125 kbit/s; a maximum total line speed of 500 m must not be exceeded.
This interface of POWERCON is a multifunctional interface that can be used as programming interface plus one of the additionally indicated tasks. If an additional function is used for program transmission (from the PC), the connector is to be temporarily replugged.
The power supply unit of POWERCON serves to supply internal, controlled system voltages and is reverse-connection protected. The supply voltage of the controller is normally 24VDC but may vary within a wide range between 9 and 30 VDC, which allows POWERCON to work properly even at the starter battery of an emergency power supply system.
POWERCON works properly with a 12 VDC system as well; however, it must be ensured that the voltage does not fall below the 9 V limit (e.g.,separate control battery).
Microprocessors only work properly within a narrow range of their supply voltage beyond this range undefined program runs may occur which may lead to serious damage at the controlled system. The following measures are intended to prevent such faults at POWERCON.
An integrated voltage monitor, which monitors the system voltage of the microcontroller, releases a hardware reset if the admissible tolerances are exceeded so that the system is restarted when the voltage is in the admissible range again (e.g., during disconnection and connection of supply voltage). The watchdog circuit is connected at an output of the micro controller and thus monitors its cycle time; in case of irregularities, a hardware reset is released, too.
The software (operating system or contact plan program) can be directly transmitted from a PC through the RS-232 interface into the controller by means of Hitzinger's programming software "Winkop". The software is directly written into the flash EPROM and stored there in a failsafe manner.
After transmission, the program can be tested in the online mode, during which the logic states of all programmed inputs, outputs, flags, etc., are read out and represented in the contact plan so that the programmed functions can be quickly checked.
Furthermore, all parameters such as software times, constants, configuration, data recorders etc., can be transmitted.
If a modem is provided at a system, it can be connected to the RS-232 interface and thus allows to remote-check the function of the system, to transmit or change various parameters or, for example, to read out the data recorder in order to reconstruct the exact course of events in case of failure.
The program memory for POWERCON is implemented by a so-called flash EPROM, where the software can be stored in a failsafe manner and reprogrammed through the RS-232 interface at any time, if required. Contrary to a normal EPROM this flash EPROM does not require any special features (ultraviolet eraser programmer, etc.).
All system variables and the records of the data recorder are stored in CMOS-RAM which is additionally buffered by a lithium battery in order to maintain the data even after the controller has been switched off.
Real Time Clock (RTC)
The real-time clock (clock module) ensures a crystal-controlled, accurate system time (and date) in POWERCON and is also buffered by the lithium battery. The time and date are also stored in the records of the data recorder in order to allow a subsequent accurate analysis of the records.
If the controller is to be integrated in a process visualization system (e.g., WINCC by Siemens), this can be implemented through the RS- interface or an external interface converter at RS-422/485.
All data, such as inputs, outputs, flags, counters, times, constants, analog values, etc., can be read out through this interface. The applied HTZ3964 protocol is explained in detail in a separate specification.
An LCD is located on the POWERCON front panel, which displays all operating messages, fault messages, measured values, parameters, etc. Texts comprised of two lines containing forty characters each can be displayed. The display has a background lighting in order to ensure proper readability also under poor lighting conditions.