DE20122525U1 - Arrangement for monitoring motor starters, has breaker in current feed line with trigger device controllable by control device via control bus depending on current through motor starters - Google Patents

Abstract

The monitoring arrangement has a measurement device (12) for measuring the current passing through each motor starter (1.1,1.2) and a breaker (5) in a current feed line (3) with an associated trigger device (6) controllable by a control device (7) via a control bus (2) depending on the current through the motor starters. A response message representing the measured current is passed from the starters to the control device over the control bus.

Description

The The invention relates to an arrangement for monitoring of a power supply line connected and over a control bus with a controller communicating engine starters.

motor starters are used to drive electric motors of a machine or plant if required - automatically or by hand - to start or stop and while Among other things, the power consumption of the connected Monitor engines, to provide protection against unpredictable engine locking guarantee. Motor starters usually have a measuring device for this purpose for measuring the current conducted by the motor starter, see above that in addition to the pure motor control, a motor starter also undertakes motor protection tasks.

A problematic and potentially dangerous Situation can always occur if a motor starter and for switching on and off of the engine provided contactor, which the power supply to the engine produces or interrupts, due to a high occurred Current flow, z. B. in a short circuit by welding his Blocked contacts or by other possibly mechanical Problems in its switchability is blocked, so that at the Motor starter connected electric motor despite an effected shutdown can not be disconnected from the power supply. Also can in caused such a case by the motor starter by short circuits or shunts fault currents occur.

Out DE-AS 29 20 188 is a circuit arrangement for monitoring the main stream of shooters become known, in which the switching state of the contactor with the measurement result of a measuring device measuring the current compared is, so in the presence of a welded or otherwise not more switchable contactor the power supply to the motor starter and thus to the motor is interrupted can be. However, this known circuit arrangement requires a connection technique with conventional wiring, where every single contact conventionally, d. H. parallel to the controller boards on site is wired. The result is a larger number of screw terminals, Input / output cards and wiring harnesses, reducing the cost of planning, Configuration and wiring increase enormously.

On the other hand helps to network individual devices, such as motor starters, via a Bus system with a control bus to reduce these costs. It will the wiring is enormously reduced by pre-wired assemblies the configuration effort is reduced and commissioning by a smaller number of screw terminals and convenient addressing over the Simplified bus software. Motor starters, which have such a control bus communicate with a controller, therefore already used successfully. The short-circuit protection and thus the protection in front of a non-switchable contactor within a to the control bus connectable motor starter will be outside of the device realized with a circuit breaker reacting to short-circuit current, In practice, several motor starters, connected to a common Power supply are connected, protected by a single circuit breaker become. However, such a proven circuit in practice can be do not prevent a contactor of a motor starter can be damaged or welded in the event of a short circuit. About that in addition, in such a way Group short-circuit protection with multiple to a common Power supply connected motor starters and only one in the power supply circuit breaker provided the calculation Short circuit protection is very complex and can lead to errors in the Lead interpretation. In particular, too high a resistance in the current-carrying Lines to limit the short-circuit current to a level lead, which below the tripping threshold of the circuit breaker, thus preventing the desired tripping. The one in this Case flowing Electricity will be most likely nevertheless to a weld lead the arranged in the motor starter contactor and subsequently a shutdown of Motor Starters prevent what a dangerous situation to lead can.

The The invention therefore has the task of an arrangement for monitoring from connected to a power supply and via a control bus with a Propose a control device to communicating motor starters, in which a detection of a blocked, for example, welded contactor done can and a deliberate shutdown of the circuit breaker within one possible short reaction time brought about can be.

to solution The object is achieved according to the invention in accordance with the Protection claim 1 specified features proposed.

advantageous Embodiments and developments of the arrangement according to the invention are the subject of the dependent claims.

To solve the problem, it is proposed that the circuit breaker is associated with a triggering device, which is provided by the Steuereinrich tion via the control bus in dependence on the measured current can be controlled. The invention therefore utilizes the characteristics of the known motor protection switches communicating with a control device via a control bus, which usually have an integrated current sensor system or a measuring device for measuring the current conducted by the motor starter, in addition to being able to connect to the control bus, in order to fulfill motor protection functions , By a simple software manipulation of the motor starter, it is possible to report back the current measured by the measuring device via the control bus to the control device, so that they can make an evaluation, such as whether a welded or damaged contactor is present within a motor starter or not. If the control device has sent a switch-off command via the control bus to a motor starter and a current that is still maintained is subsequently fed back by the measuring device of the addressed motor starter, the contactor of the addressed motor starter has not switched properly. It can now be addressed by the control device via the control bus, the triggering device, which in turn activates and opens the circuit breaker, so that the unwanted current flow is interrupted and the system is transferred to a safe state. There is therefore an activation of the triggering device for the circuit breaker by the control device via the control bus as a function of the measured current in the respective motor starters, ie as a function of the current conducted by the respective motor starter.

It not only the actual measured current from the motor starters reported back to the controller but only one representing the measured current Feedback, d. H. present or absent current flow, resulting in a Simplification of over the control bus leads back to the controller feedback data leads.

Of the Control bus of the arrangement according to the invention can be used in particular as so-called AS-Interface bus system, short ASi bus system be formed, which is known per se and for binary sensors (Opener-, normally open and auxiliary contacts) and actuators (relays, contactors, lamps) in the lowest field level is designed.

The triggering device for the Circuit breaker can be an ASi slave communicating with the control bus and a controllable U or A trigger included in this known manner either falls below a certain voltage (U-trigger) or exceeded a certain current value (A-trigger) is activated and the Circuit breaker in the desired Way to interrupt the power supply lines.

Further can the power supply in a conventional manner as an energy bus be formed so that at least one, but preferably one Variety of motor starters on the one hand to the power supply and on the other hand connected to the control bus, all of these Motor starters over a common control device controllable and with a single in the power supply arranged circuit breaker are protected.

Further embodiments and details of the invention are described below with reference to the embodiment in the 1 explained in more detail.

The 1 shows several motor starters 1.1 . 1.2 , the input side via power supply cables 11 to a three-phase power supply line 3 with phases 3.1 . 3.2 . 3.3 are connected. The power supply line 3 is executed here as an energy bus. The presentation with two motor starters 1.1 and 1.2 is merely to be considered as an example, it can be provided in the same arrangement, only one motor starter or more than two such motor starters.

The one from each phase 3.1 . 3.2 . 3.3 branched off power connection lines 11 are by the motor starters 1.1 . 1.2 through to one each to the respective motor starter 1.1 . 1.2 connected electric motor 4 passed.

Every motor starter 1.1 . 1.2 as well as any further number of further not shown here to the power supply line 3 connectable motor starters each include a contactor 10 with main contacts 10.1 . 10.2 . 10.3 , which are operated simultaneously and each one phase of the power supply line 11 to the engine 4 turn.

In addition, every motor starter includes 1.1 . 1.2 a measuring device 12 , by means of which by the motor starter 1.1 respectively. 1.2 from the power supply 3 to the engine 4 Guided current can be measured so that the electric motor 4 is protected from damage in a conventional manner.

The switching commands for opening or closing the contactor 10 inside the motor starter 1.1 respectively. 1.2 can either from here not shown, to the motor starters 1.1 . 1.2 arranged hand switches or by a control device 7 , z. B. a PLC can be effected via a control bus 2 For example, an ASi bus with the individual motor starters 1.1 . 1.2 by a corresponding addressing of the same communicates. For this purpose, every motor starter 1.1 . 1.2 over a bus line 13 to the tax bus 2 connected, allowing bidirectional communication between the control device 7 and the motor starters 1.1 . 1.2 is possible.

All on the one hand to the power supply 3 connected and on the other hand via the control bus 2 with the control device 7 communicating motor starters 1.1 . 1.2 are also against a possible short circuit together by a in the power supply 3 integrated circuit breaker 5 secured, in the presence of ei nes short-circuit current of, for example, more than 280 A, the current flow through the power supply line 3 interrupts the motor starters 1.1 . 1.2 to protect against damage and to avert danger.

In practice, especially when connecting a plurality of motor starters 1.1 . 1.2 and other such motor starters to a common power supply 3 the design of the circuit breaker 5 and the calculation of the required trip current value difficult because too high a resistance in the current-carrying lines to a limitation of the short-circuit current to below the tripping value of the circuit breaker 5 lying level and thus the tripping of the circuit breaker 5 although the current flowing in this case is most likely to weld one or more contactors 10 can lead.

In addition, also mechanical or other damage to the shooter 10 the motor starter 1.1 . 1.2 occur during operation, the following a desired opening of the contactor and thus stopping the connected electric motor 4 prevention.

To counteract this undesirable and potentially dangerous circumstance is a triggering device 6 with an ASi slave 60 and one with this via control lines 61 connected U or A trigger 50 provided, in turn, a trip of the circuit breaker 5 in the power supply line 3 can cause. The ASi slave 60 communicates via another bus line 600 with the tax bus 2 and thus with the tax to the bus 2 connected control device 7 and is directly accessible from this via a corresponding addressing.

Is it now during operation in the 1 illustrated arrangement to a fault of a contactor 10 within a motor starter 1.1 respectively. 1.2 , For example, by welding the main contacts 10.1 . 10.2 . 10.3 or mechanical damage, leaving the previously closed contactor 10 can not be opened, so flows freely from the power supply line 3 to the electric motor 4 and initiates its operation.

Will now be from the controller 7 via the tax bus 2 by appropriate addressing, for example to the motor starter 1.1 issued a switch-off and leaves its contactor 10 z. B. due to welded main contacts 10.1 . 10.2 . 10.3 do not open, the current flows to the electric motor despite the corresponding switch-off command 4 and is about the measuring device 12 of the engine starter 1.1 measured. The motor starter 1.1 Now, after receiving the turn-off command addressed to him as feedback, he still gives his measuring device 12 measured current via the bus line 13 on the control bus 2 and thus to the controller 7 which, in turn, can detect the non-execution of the desired switching command based on this information. Immediately afterwards, the controller speaks 7 via the tax bus 2 the by means of the bus line 600 connected ASi slave 60 on, now the U or A trigger 50 pressed, so in the immediate consequence of the trigger 50 connected circuit breaker 5 opens and thus the power supply line 3 interrupts, so that the unwanted current flow is interrupted and the entire system is transferred to a safe state.

Subsequently, at the control device, the location of the error that has occurred, here motor starter 1.1 be queried and corrected accordingly.

In contrast, when an undamaged contactor 10 of the engine starter 1.1 immediately after receipt of a turn-off command from the controller 7 via the tax bus 2 the contactor 10 actuated accordingly and in the respective motor starter 1.1 respectively. 1.2 arranged measuring device 12 now no longer detects flowing current, which is the corresponding confirmation of the control device 7 via the tax bus 2 can be confirmed, so there is no reason, the ASi slave 60 to open the circuit breaker 5 to press.

The advantage of the arrangement described above is in particular that a plurality of motor starters 1.1 . 1.2 etc. to a common and with only a circuit breaker 5 secured power supply 3 can be connected, wherein by direct evaluation of a switching command of the control device 7 following current flow through the addressed motor starter 1.1 respectively. 1.2 the function of the respective motor starter 1.1 . 1.2 provided contactor 10 checked and in the presence of an irregularity immediately the entire current flow through opening the circuit breaker 5 can be interrupted by the controller. In addition, the arrangement according to the invention can be easily applied to existing with a control bus 2 , especially ASi-bus networked motor starters Retrofit, since only one ASi slave 60 with corresponding U or A trigger 50 that on the circuit breaker 5 acts on the tax bus 2 connected and the control device 7 must be programmed accordingly. Such retrofitting is possible even during operation of already existing systems.

The arrangement described above enables a detection of a fault present in a motor starter and a deliberate shutdown of the circuit breaker 5 within a reaction time of 20 to 50 ms.

Claims (9)

Arrangement for monitoring to a power supply line ( 3 ) and via a control bus ( 2 ) with a control device ( 7 ) communicating motor starters ( 1.1 . 1.2 ), whereby each motor starter ( 1.1 . 1.2 ) a measuring device ( 12 ) for measuring by the motor starter ( 1.1 . 1.2 ) and in the power supply line ( 3 ) a circuit breaker ( 5 ) and the circuit breaker ( 5 ) a triggering device ( 6 ) assigned by the control device ( 7 ) via the control bus ( 2 ) as a function of the motor starter ( 1.1 . 1.2 ) conducted current is controllable. Arrangement according to claim 1, characterized in that of the motor starters ( 1.1 . 1.2 ) a feedback representing the measured current via the control bus ( 2 ) to the control device ( 7 ) is deliverable. Arrangement according to one of claims 1 or 2, characterized in that the triggering device ( 6 ) from the control device ( 7 ) in the presence of a taxpayer ( 2 ) to a motor starter ( 1.1 . 1.2 ) and a subsequent from the measuring device ( 12 ) of the addressed motor starter ( 1.1 respectively. 1.2 ) measured current can be controlled. Arrangement according to one of claims 1 to 3, characterized in that the circuit breaker ( 5 ) by means of the control device ( 7 ) triggered triggering device ( 6 ) is openable. Arrangement according to one of Claims 1 to 4, characterized in that the control bus ( 2 ) is designed as an ASi bus. Arrangement according to one of claims 1 to 5, characterized in that the triggering device ( 6 ) one with the control bus ( 2 ) ASi slave ( 60 ) and a controllable U or A trigger ( 50 ). Arrangement according to one of claims 1 to 6, characterized in that the power supply line ( 3 ) is designed as an energy bus. Arrangement according to one of claims 1 to 7, characterized in that at least two motor starters ( 1.1 . 1.2 ) are provided. Arrangement according to one of claims 1 to 8, characterized in that the motor starters ( 1.1 . 1.2 ) to a common power supply ( 3 ) are connected.