Abstract:
A mobile high voltage network supplies electrical consumer units connected via a plug-in connector and can be switched on and off by means of mechanical switches, with a fuse responding in the event of a short circuit. The high voltage network carries a direct voltage and to each electrical consumer unit ( 8; 10 ) a separate diagnostic and protection monitoring system is assigned which is activated when it is switched on and/or off. Such a direct voltage and high voltage network in conjunction with the diagnostic and protection monitoring system makes it possible, before starting up any circuit of consumer units, to effect a self-diagnosis of the protection monitoring system, to ensure that all components are fully functional. Without this, self-diagnosis with proof of functionality the relevant circuit of consumer units is not switched on.

Description:
BACKGROUND OF THE INVENTION 
   The invention relates to a mobile high voltage network to supply an electrical consumer unit connected by a plug-in connector and which can be actuated by means of mechanical switches, with a fuse responding in the event of a short-circuit. 
   So far, few applications have been known for the mobile use of electrical networks of high power transmission. Basically, the conditions and solutions which have become known from stationary high voltage networks have been taken as the basis for this. With such networks, for which only alternating voltages are customary, cable breakage and the separating of connection couplings under load on account of the zero passage of the voltage gradient cause no problems. With a view to the greatest possible flexibility, a high degree of efficiency, a low expenditure on components, as well as a reasonably priced solution, including the expenditure on power electronics, the loss through the power electronics, as well as the expenditure for the stabilization of the network frequency and the network voltage, it has thus far been uneconomic for power transmission by means of high voltage networks based on alternating or direct current. 
   In the mobile field, electronically controlled and monitored technical devices have become known already which are capable of self-diagnostic checking. That means that during operation, faults which occur are detected and appropriate actions are instigated. 
   The task of the invention lies in creating a mobile high voltage network of the type described in the introduction hereto, that is economic to operate and to monitor. 
   This task is solved by the fact that the mobile high voltage network carries a direct voltage, and a separate diagnostic and protection monitoring system is assigned to each electrical consumer unit or load. Such a mobile high voltage network, in conjunction with the diagnostic and protection monitoring makes it possible, before the starting up of any consumer circuit, to carry out the protective monitoring so as to ensure that all the components are fully operational. Without this self-diagnostic check with proof of the capacity to operate, the relevant consumer circuit is not connected. 
   The diagnostic and protective monitoring device detects insulation faults and faults of the electrical connection. The diagnostic and protective monitoring device also prevents any separation of the electrical connector when live. In the event of too high electrical current, a fuse prevents the overloading of the diagnostic and protective monitoring device and the electrical line connections and junctions. 
   The diagnostic and protection monitoring is, however, also used to regulate the switching off of the consumer so that the network connection can be separated. For this, the consumer is disconnected from the high voltage network and the remaining network circuits are monitored to see if they are live. In particular, consumers with stored energy—electrical accumulators or also machines, which on stopping still feed current into the consumer—are transferred via a short-circuit connection into the safe condition with no voltage and no current. As soon as the consumer has definitely reached the condition where there is no voltage, the protection monitoring releases the plug-in connection for the separation. 
   This allows a separation of components carrying D.C. voltage, without the surrounding medium being ionized and without any arc occurring. The current can therefore be safely interrupted. In this way, no special protection medium, (e.g. hydrogen) is needed in the contact area and devices to blow out arcs. The operational reliability is increased many times more that with so far customary devices which use protection gas and arc blow-devices. The occurrence of an arc is excluded by the proposed solution. There is, therefore, no burning off of the contacts, nor is any device needed to extinguish arcs. Over the whole lifespan, without any additional measures the operational reliability of the diagnostic and monitoring, protection is therefore guaranteed. Through the monitoring of insulation faults, line breakage, or too great a flow of power, it is guaranteed that no danger arises when using electronically operated machines through the high voltage network. 
   The parallel circuit of a mechanical switch and a power switch makes it possible to use the advantageous properties and characteristics of these components to the base advantage. Thus, electronic power switches are in a position to by-pass relatively large potential differences with arc formation, whilst mechanical switches are very prone to this. 
   On the other hand, electronic power switches, unlike mechanical switches, exhibit high losses. When following the stated method of switching both when switching on and switching off the consumer, due to the effective electronic power switches, on the mechanical switch, there is a very slight voltage difference, which cannot adequately ionize the environment so as to cause no arcs. In addition, with the consumer switched on, only a slight drop in power is detected at the switches. The degree of effectiveness of the switching device is higher, and the thermal incidence, which is slight on account of the reduces loss of power, can be dissipated to the environment without additional cooling devices. 
   The features of the invention bring about on the mechanical switches certain preset voltage levels, which make it possible to establish the proper function of the switches. In addition, the current path takes over the dissipation of the slight leakage current of the power switches, in order to definitely exclude burning off on the contacts. 
   Due to the features of the invention, the plug-in connector cannot be separated when it is under electrical voltage. Therefore, any danger from the occurrence of an arc or contact with live components is excluded. Only in the state where there is no current and no voltage can the connector be disconnected. 
   The features of the invention make it possible for the diagnostic device to detect potential changes on the screening line, which occur in the event of damage in the insulation fitted between the line carrying current and the protection line through external effects or the interruption of the screening line. The network is then reliably switched off, so that there can be no danger from any damaged line. It is, therefore, guaranteed that the essentially higher probability of the occurrence of harmful effects on the lines in mobile use is not faced with a higher danger potential. 
   The features of the invention ensure the detection of insulation faults or line interruptions of lines from both the positive and negative pins. 
   Further advantageous details and features of the invention can be seen in the claims. 
   The invention is explained in greater detail hereinafter by reference to the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a circuit diagram of a diagnostic and protection monitoring system with socket connected to the + pin and the − pin of a D.C. voltage source. 
       FIG. 2  is a circuit diagram of a simple electrical consumer which is connected by means of a plug to the diagnostic and protection monitoring system in accordance with  FIG. 1 . 
       FIG. 3  is a circuit diagram of an electrical consumer with a further diagnostic and protection monitoring system which can be connected by means of a socket to the diagnostic and protection monitoring system in accordance with  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In  FIG. 1 , only the positive pin P and the negative pin M of a mobile high voltage network can be fed by a suitable D.C. current generator, which is not shown. An electrical consumer  8  (see  FIG. 2 ) is connected to these pins, with a diagnostic and protection monitoring device accommodated in an insulated casing  1 . A plug-in connector  2  facilitates the connection of the electrical consumer  8  to the high voltage network. The plug-in connector  2  is secured against disconnection in situations which are not allowed by means of a mechanical lock  3 . 
   In a positive line between the positive pin P and a first contact  4  of a socket of the connector  2 , in series behind each other, there is a fuse Si 1 , an electronic power switch T 1 , a mechanical switch S 2 , and an ammeter device i. In a negative line between the negative pin M and a second contact  5  of the socket, in series behind each other, there is a fuse Si 2 , an electronic power switch T 3 , and a mechanical switch S 4 . A mechanical switch S 1 , S 3  is connected in parallel to each of power switches T 1  and T 3 . In the direction of the current flow behind the power switches between the positive line and the negative line, a power switch T 2  is located. The network further comprises a resistor series circuit consisting of three identical high-impedance resistors R 3 , R 4 , R 5  whereby the voltage between the resistors R 3  and R 4  is applied to the free contact of switch S 2  and a voltage between R 4  and R 5  is applied to the free contact of switch S 4 . 
   To generate a reference potential, there is a further resistance series circuit before fuses Si 1  and Si 2  between the positive line and the negative line consisting of two identical high-impedance resistors R 1 , R 2 . The reference potential is defined as the average potential occurring between the resistors, which is fed via the third contact  6  of the socket into the one protection line  7  of the connected consumer  8 . The other protection line  7   a  of the consumer  8  is connected to a fourth contact  13  of the connector, from where there is an electrical connection for a diagnostic evaluation device  9 . The protection lines  7  and  7   a  are surrounded by an insulating layer and this again surrounds the current-carrying lines leaving contacts  4 ,  5 . 
   The consumer  8  may be located alone or in series with further consumer units in a consumer unit circuit. “In series” here does not mean an electronic series circuit, where an electric current flows through every consumer unit and a part of the mains voltage is dissipated. Instead, here it means an stacked arrangement of consumer units, where each connected consumer unit makes available a voltage source for a further consumer unit, as explained below in connection with  FIG. 3 . 
   The drawing shows, in the form of latched lines, control lines for the control of switches S 1 , T 1 , S 3 , T 3 , T 2 , S 2 , S 4  lines for the transmission of the measured values of the ammeter device i, as well as lines for the transmission of voltage values to the measuring points u 1 , u 2 , u 3 , u 4 , u 5  and u 6  of the protection monitoring system. These lines are connected to an evaluation device  9 , which makes the protection monitoring capable of self-diagnosis. 
     FIG. 3  shows an electrical consumer  10  connected to the protection monitoring in accordance with  FIG. 1  by means of a further unit  11 , from which a still further electrical consumer can be supplied with electrical power via a plug-in connection  12 . The further electrical consumer  11  again includes a diagnostic and protection monitoring system of the same kind as described in  FIG. 1 . The reference potential generated by the resistors R 1 , R 2  of  FIG. 1  is used in the further electrical consumer  11  so that in the event of a fault a high-impedance contact protection is guaranteed. 
   For the constant monitoring of protection line  7  by the evaluation device  9  (to check for continuous flow and passage), a reference potential is connected via the protection line  7  of a connected consumer unit  10  to the third contact  6  of the diagnostic and protection monitoring system which is in the further electrical consumer  11 . This reference potential is also connected to a normally closed contact S 5 . The normally closed contact S 5  is opened, if via the connector  12  a further consumer unit is connected, and closed, if the connector is disconnected. 
   In the open condition of the normally closed contact S 5 , that is if a further consumer unit is connected, the direct connection between protection lines  7  and  7   a  is interrupted. A reference potential is connected from the third contact  6  of connector  12  to the evaluation unit  9  of  FIG. 3  and via resistor R 6  and line  7   a  to the fourth contact  13  of  FIG. 1  and hence to the evaluation device  9  of  FIG. 1 . 
   Method of Operation of the Diagnostic and Protection Monitoring System: 
   Switching on the Consumer Unit: 
   If the supply is guaranteed by the generator the positive and negative voltages are measured at measuring points u 1 , u 2  against the reference potential produced by the resistors R 1 , R 2 . If the fuse Si 1 , Si 2  are in order and switchers S 1 , S 3  are open, then the electronic power switched T 1 , T 2  and T 3  in the disconnected condition act like resistors in series between the + pin and − pin. Between measuring points u 1  and u 3 , u 3  and u 4 , as well as between u 4  and u 2  characteristic voltages can then be measured. If these voltages to zero, then power switches T 1 , T 2  and T 3  are safely disconnected. 
   Switches, S 2  S 4  are open if between measuring points u 3  and u 5 , as well as between u 4  and u 6 , the voltages corresponding to the resistance series circuit from resistors R 3 , R 4  and R 5  are present. 
   If this condition is present, then in the first instance switches S 2 , S 4  are closed. Now, the voltages between measuring points u 3  and u 5 , as well as between u 4  and u 6 , drop to zero volts. On the next opening of switches S 2 , S 4 , the voltages must rise again. 
   The next step is that power switch T 2  is switched on. The voltage between measuring point u 3  and u 4  must now decrease with the voltage drop of power switch T 2  in the connected condition. If this happens, then power switch T 2  is in order and it is switched off again. 
   Power switches T 1 , T 3  can now be switched on, and the voltages between measuring point u 1  and u 3 , as well as between u 4  and u 2  must go typically from 2V to &lt;4V in response to the voltage drop at the power switches T 1  and T 3 . Then, power switches T 1  and T 3  are again switched off and the voltages rise again. 
   Switches S 1 , and S 3  can now be switched on, and the voltages between measuring points u 1  and u 3 , as well as between u 4  and u 2 , must properly got to 0V. 
   Then switches S 1  and S 3  are switched off again, whereupon with perfect operation, the voltages rise again. 
   Now, switches S 2  and S 4  are closed, and power switch T 3  is switched on. The voltage between the measuring point u 4  and u 2  must decrease with the known voltage drop of power switch T 3 . This ensures that this switch is switched on. Now, switch S 3 , which has the task of minimizing the loss of power switch T 3 , is closed. 
   Power switch T 1  is now switched on again, and the voltage supply occurs on connector  2  and electrical consumer  8 , which is connected thereto. In order to minimize the power losses on power switch T 1 , switch S 1  is then switched on, and power switch T 1  is switched off. 
   The described procedure of switching on may only take place if protection lines,  7 ,  7   a  for the onward passage of the reference potential do completely allow passage and no interruptions occur. 
   Switching off the Electrical Consumer: 
   The switch-off procedure begins with the opening of switches S 1  and S 3 . Then, power switch T 1  is switched off and power switch T 2  is switched on. Since via the consumer, which can also work as a generator, voltage can be fed in, a short circuit is necessary via power switch T 2 , so that the voltage in this case does not rise too high, if there is no protection device for this in the consumer. 
   As soon as the ammeter device i establishes that no further current is flowing (consumer  8  no longer working as a generator), switches S 2  and S 4  are opened. 
   The switching off of switches S 2 , S 4  is checked by measuring voltage between measuring points u 3  and u 5  or u 4  and u 6 . If the switching off was unsuccessful, power switches T 3  and T 2  are switched off. 
   Faults: 
   
       
       Power switch T 1  does not switch on: 
     
  
   This can be discovered when switching on by voltage measurement between measuring point u 1  and u 3 .
     Consequence: no switching on possible.   Power switch T 1  does not switch off:   

   This can be discovered when a power switch T 1  is switched on and/or off. If a defect is found, then the switch-on procedure can not be affected. 
   When switching off, by short-circuiting the power switch T 2 , the voltage at measuring points u 1 , u 3  and u 5  collapses. The short-circuit current destroys the fuse Si 1  or Si 2 . As soon as it is no longer possible to establish any further current via ammeter device i, then complete switching off is effected. Consequence: no further switching on possible; by voltage measurement between measuring point u 1  and u 3 , it is possible to discover any defect of the fuse or defect of power switch T 1 .
     Power Switch T 3  does not Switch on:   

   This can be discovered when switching on by measuring voltage between measuring points u 2  and u 4 .
     Consequence: no switching on possible.   Power switch T 3  does not switch off:   

   When testing a switching function it is already possible to discover whether power switch T 3  switches on and off. If a defect is found, then the switching-on procedure can no longer be effected. 
   When switching off, faulty operation can be discovered by measuring the voltage between measuring points u 2  and u 4 . If power switch T 3  does not switch off, then nonetheless connector  2  can be switched off, the network is separated safely by switches S 2  and S 4 .
     Consequence: no Switching on possible.   Power switch T 2  does not switch on:   

   This can be discovered when switching on between measuring points u 3  and u 4 .
     Consequence: no switching on possible, when switching off the mains connection, with the consumers working as generators an intolerably high voltage may occur.   Power switch T 2  does not switch off:   

   During the switch-on test or when switching off, this can be discovered by measuring between measuring points u 3  and u 4 .
     Consequence: no further switching on possible, since otherwise there is a short circuit. Safe switching off is possible.   Fault on switch S 1 : corresponding fault on power switch T 1 .   Fault on switch S 3 : corresponding fault on power switch T 3 .   Fault on switches S 2 , S 4 :   

   This is checked during the switch-on test operation, and can be discovered via voltage between measuring points u 3  and u 5  or u 4  and u 6 . 
   Consequence: no further switching on possible; cannot be opened when switching on switches S 2 , S 4 , power switches T 2  and T 3  remain switched on. 
   Prevention of Arcs: 
   The on/off switching procedure is accomplished with electronic power switches T 1 , T 3  and mechanical switches S 1 , S 2 , S 3  and S 4 . The on/off switching procedure and the ammeter device prevent the occurrence of an arc on switches S 1 , S 2 , S 3  and S 4  either through reduction to very low switching voltages or very high-impedance current paths. 
   The occurrence of an arc in the connector is prevented by the fact that this can only be separated via a controlled locking device, if the mains voltage to the connector is switched off. 
   If an arc occurs through mechanical effects on the current-carrying line to consumer  8 , which is protected by protection line  7 , then this is detected by protection line  7  through a voltage drop or voltage rise of the reference voltage and the mains voltage is switched off. 
   Interruption of the Protection Line: 
   Protection line  7  is constantly monitored by the evaluation device  9  for full flow and passage. For this, the reference potential is connected via protection line  7  of a connected consumer  8  to the evaluation device  9  ( FIG. 1 ). If, as shown in  FIG. 3 , a connected consumer  10  comprises a connector  12  and provides for the connection of a further consumer, then connection of all the connected consumers is assured. 
   In this case the connection of the protection line to the previously connected consumer  10  is to be cancelled and the last consumer unit in the series must make the connection to the evaluation device  9 . 
   As soon as an interruption of the protection line is discovered, evaluation device  9  switches off the mains for this circuit of consumer units. 
   In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.