DE102017202476B4 - Device for functional testing of a relay - Google Patents

Abstract

Device for functional testing of a relay with a coil circuit for controlling the relay coil and at least one switching level, characterized in that the device has a switching matrix consisting of 144 optocouplers with MOSFET outputs.

Description

The invention relates to a device for functional testing of a relay with a coil circuit for controlling the relay coil and at least one switching level. To check and maintain the functionality of a relay, it is necessary to periodically determine a pull-in and drop-off voltage, a coil current and a rated current and a nominal voltage of the relay.

In the prior art, the tester determines the function of the relay to be tested with simultaneous measurement of the contact contact resistance and an optical display of the determined resistance

The old tester was used to dynamically test the contact resistances of conventional railway signal combs.

This tester is about 35 years old, therefore, the individual test methods are outdated. To operate and adjust the tester, test cards in the form of templates were necessary. Here were all necessary information such as switch positions and assignments of the display LED to a specific contact included. The test did not start automatically. Some settings had to be made. This can lead to disturbances in the test procedure. In addition, there were no possibilities for comparison of the test results due to differently practiced measuring methods.

The patent US 2004/0 085 071 A1 discloses an apparatus for testing an electrical relay having a portable housing and an electrical test circuit within the housing to perform a variety of types of tests on the relay.

In the patent US Pat. No. 6,377,051 B1 Become a relay test kit with reduced size and weight containing a small, highly efficient voltage and current source. The test kit incorporates a class D switching amplifier design that greatly reduces the size of the power source needed to inject the correct voltage and current into the secondary inputs of a protection relay. To further reduce the size, weight, and cost of the relay tester, a single voltage amplifier is used to drive both the secondary inputs and the secondary inputs of a protection relay. In this way, this test set becomes both a voltage converter and a current transformer simulator using a single voltage source of reduced size, weight and cost. In order to make the current source variable while maintaining accuracy, a microcomputer module is used to monitor both the current and the voltage being fed to the protection relay. This microcomputer can also automatically perform the required relay tests and direct the voltage or current to the corresponding inputs of the protection relay by direct control of a relay matrix.

Both patents describe devices for testing relays using a switching matrix.

In the prior art is the patent DE 10 2015 211 510 A1 known. The invention relates to a device for monitoring the operability of at least one switch (Rel-L1, Rel-N, Rel-PE), wherein via a signal generator (S) and at least one capacitor (C2) an AC signal (U _TR ) in the Current path of the switch to be monitored (Rel-PE) is coupled and wherein the AC voltage signal (U _TR ) via at least one further capacitor (C1) for detecting an output voltage (U-out) is coupled out again. The invention is characterized in that no output voltage (U-out) is applied when the at least one switch (Rel-PE) is closed.

From the DE 297 21 675 U1 a circuit arrangement for functional testing of an electrical circuit is known, wherein the circuit comprises an electromechanical switching element, in particular a trigger of a high-voltage circuit breaker, which is electrically connected in series with two electrical switching elements and arranged electrically between them. The patent shows examples of the use of an optocoupler in relay testing.

With the state-of-the-art comb relay tester, comb relays are to be tested for function during maintenance, repair and troubleshooting. At the same time, the contact resistance of the contacts as well as the resistance of the switching levels with each other is determined.

With the state-of-the-art comb relay tester, comb relays are to be tested for function during maintenance, repair and troubleshooting. At the same time, the contact resistance of the contacts as well as the resistance of the switching levels with each other is determined

It is therefore an object of the invention to provide a device for functional testing of relays, in particular comb relay, with a coil circuit for driving the relay coil and at least one switching level, in which the described disadvantages of the prior art are achieved.

According to the invention, this object is achieved by the features listed in claim 1. Further advantageous embodiments of the invention are illustrated in the subclaims.

The test method according to the invention allows a quick and easy test of a relay. It is an integrated, multi-purpose test instrument that minimizes labor and time and ensures consistent quality. The tester serves to check all embodiments of relays.

The test device is to be used with comb relay which can be used by DB Netz AG in the remote control systems DUS501 / 502 and can test these by a dynamic test procedure.

A comb relay consists of one or two windings whose tightening torque is used at current flow to move a mechanical armature. which closes or opens one or more relay contacts. These tongues to be moved these contacts are positively connected to each other via a thin plastic plate and therefore can only be moved together. This design feature is reason for the designation comb relay.

The comb relays are identified by a unique alphanumeric manufacturer number and have special relay data stored in a database on the tester.

• • Milliohmmessung mit Schaltmatrix Hier wird eine Vierleitermessung zur Bestimmung der Widerstände eingesetzt. Die Vierleitermessung wird vor allem bei der Messung kleiner Widerstände eingesetzt, wenn die parasitären Widerstände von Zuleitungen und Kontaktstellen nicht mehr vernachlässigbar klein gegenüber dem zu messenden Widerstand sind. Die Vierleitermessung wird verwendet zur Bestimmung der Kontaktwiderstände der Öffner im abgefallenen Zustand, sowie der Schließer im angezogenen Zustand des Relais.
• • Hochohmmessung mit Schaltmatrix Eine einfache Widerstandsmessung zur Bestimmung von hochohmigen Widerständen. Die Hochohmmessung wird Verwendet zur Bestimmung der Kontaktwiderstände der Öffner im angezogenen Zustand, sowie der Schließer im abgefallenen Zustand des Relais. Zusätzlich auch zur Ermittlung der Widerständen zwischen allen Schaltungsebenen, inkl. der Wicklungsebene.
• • Kontaktanschluss-Übergangswiderstandsmessung Kombination der beiden oben beschriebenen Messschaltungen. Diese Messung wird verwendet um den Übergangswiderstand der einzelnen Kontaktanschlüsse zu messen.

With the tester, two differently designed measuring circuits can be switched. A third measuring variant can be carried out by a combination of both circuits.

• • Milliohm measurement with switching matrix Here, a four-wire measurement is used to determine the resistances. The four-wire measurement is mainly used in the measurement of small resistors, when the parasitic resistances of leads and contact points are no longer negligible compared to the resistance to be measured. The four-wire measurement is used to determine the contact resistance of the normally closed contacts in the de-energized state, as well as the normally open contact in the energized state of the relay.
• • High impedance measurement with switching matrix A simple resistance measurement for the determination of high-resistance resistors. The high-ohm measurement is used to determine the contact resistance of the normally closed contact in the attracted state, as well as the normally open contact in the disconnected state of the relay. In addition also for the determination of the resistances between all circuit levels, incl. The winding level.
• • Contact connection contact resistance measurement Combination of the two measuring circuits described above. This measurement is used to measure the contact resistance of the individual contact terminals.

The switching matrix consists of 144 optocouplers with MOSFET outputs and is used to switch between the terminals of the relay, so that the different switching levels can be measured independently.

The optocouplers are controlled by μC via two port extensions (IC3 and IC5) so that the corresponding optocouplers are always active at the same time. The active optocouplers each switch their signal to a terminal of the corresponding two-pole Kelvin contact. This ensures that the positive side of the current source with the positive side of the voltage measurement is connected together to the same terminal of the relay. The same applies to the negative sides.

• 1 zeigt das Blockschaltbild der Gesamtschaltung
• 2 zeigt einen Ausschnitt der Schaltmatrix
• 3 zeigt die Konstantstromquelle
• 4 zeigt die Spannungsmesseinrichtung für die Milliohmmessung
• 5 zeigt die Spannungsquelle für die Hochohmmessung
• 6 zeigt die Messschaltung für die Hochohmmessung

The drawings show in

• 1 shows the block diagram of the overall circuit
• 2 shows a section of the switching matrix
• 3 shows the constant current source
• 4 shows the voltage measuring device for the Milliohmmessung
• 5 shows the voltage source for the high-impedance measurement
• 6 shows the measuring circuit for the high-resistance measurement

1 shows the block diagram of the total measuring circuit

• - Das Netzteil stellt die Spannung für die Ansteuerung des Prüflings (Kammrelais) in der Höhe von 2V bis 110V und die Versorgungsspannung für die Hochohmmessung (U_Einspeisung für ISO) von 60V bereit.
• - Die „U_Einspeisung für ISO“ begrenzt die Versorgungsspannung auf 55V sowie den maximalen Strom auf 1mA für die Hochohmmessung
• - Die „U_Messung für ISO“ generiert eine Spannung im Verhältnis zur Formel $$Rx=Rg\left(\frac{Uiso}{Ug}-1\right)Rx=Rg\left(\frac{Uiso}{Ug}-1\right)$$
  
  die zur Messung an dem Mikrokontroller weitergeleitet wird. Wobei:
  • R_x dem zumessenden Widerstand entspricht.
  • U_iso der Versorgungsspannung hier 55V
  • R_g der interner Messwiderstand und
  • U_g die Messspannung
  Entspricht.

• - Die „Konstantstromquelle“ stellt den benötigten konstant Strom für die Milliohmmessung bereit.
• - Die „ΔU_Messung für mΩ“ ermittelt den Spannungsabfall der über der zu messenden Schaltebene Abfällt.
• - Der „Prüfling“ steht Symbolisch für das zu vermessende Kammrelais.
• - Die „Matrix“ in der Mitte der Darstellung wird vom Prozessor aus in der Form angesteuert, dass Nacheinander alle Isolations- und Übergangswiderstände gemessen werden können.

In the block diagram, the measuring circuit is divided into essential parts.

• - The power supply provides the voltage for the control of the device under test (comb relay) in the amount of 2V to 110V and the supply voltage for the high impedance measurement (U _supply for ISO) of 60V.
• - The "U _feed for ISO" limits the supply voltage to 55V and the maximum current of 1mA for the Hochohmmessung
• - The "U _Measurement for ISO" generates a voltage in relation to the formula $$Rx=RG\left(\frac{UisO}{UG}-1\right)Rx=RG\left(\frac{UisO}{UG}-1\right)$$
  
  which is passed on to the microcontroller for measurement. In which:
  • R _x corresponds to the measured resistance.
  • U _iso the supply voltage here 55V
  • R _{g is} the internal measuring resistor and
  • U _g the measuring voltage
  Complies.

• - The "constant current source" provides the required constant current for the Milliohmmessung.
• - The "ΔU _measurement for mΩ" determines the voltage drop of the over the to be measured switching level drops.
• - The "test item" symbolizes the comb relay to be measured.
• - The "matrix" in the middle of the display is controlled by the processor in the form that successively all insulation and contact resistance can be measured.

2 Switching matrix with optocoupler MOSFETs

This figure shows the excerpt from the switching matrix which is responsible for the milliohm measurement. Here is a 100mΩ resistor on the upper side in the middle, this is used for the self-test. This is controlled via the control lines 1P7 and 2P7. Furthermore, the control line 1P31 for IC65 must also be switched. This is necessary so that the signal to be measured is forwarded to the measuring circuit. Here you can see that the optocouplers are always driven in pairs. Vertically in the middle of the lines are led to a data bus, which are led to the designated Kelvin contacts. With these Kelvin contacts the connection to the comb relay is made.

• • Milliohmmessung mit Schaltmatrix

In detail, the functions are described as follows:

• • Milliohm measurement with switching matrix

The range of Milliohmmessung with switching matrix is divided into three circuit parts. These are the constant current source, a very high-voltage voltage measurement and amplification as well as the switching matrix. The gain of the instrumentation amplifier is switched. The reinforcements are 10, 100, 1000 drawer.

zur Folge.The constant current source, as in 3 shown, consists of an operational amplifier circuit with IC1 and its components R1 . R2 . R3 . LED1 and Q4 , With R3 and the LED1, a reference voltage is generated for the operational amplifier (OP), the over R2 is provided at the positive entrance. If the output of the OP is now connected by adding a measured object, this now attempts a voltage drop in the height of the reference voltage R1 to create. This has a current flow of $$\begin{array}{l}\text{I}=\text{U / R}\\ \Rightarrow \text{I}=\text{Uref / R3}\\ \Rightarrow \text{I}=\text{1}\text{6V / 75ohm}\\ \Rightarrow \text{I}=\text{21}\text{, 33 mA}\end{array}$$

result.

With the help of MOSFET Q4, the output of the constant current source can be short-circuited to protect the device under test

The high-impedance voltage measurement consists of the instrument amplifier (Inst-OP) IC4 and the downstream operational amplifier IC2. The Inst-OP amplifies and decouples the voltage measured at the device under test (GOhm). The downstream operational amplifier (OP) IC2 is connected as a voltage follower, so that the load of the subsequent analog-to-digital converter (ADC) has no influence on the measurement signal.

The switching matrix between these two circuit parts consists of 76 optocouplers with MOSFET outputs and is used to switch between the terminals of the relay, so that the different switching levels can be measured independently. The optocouplers are controlled by μC via two port extensions (IC3 and IC5) so that the corresponding optocouplers are always active at the same time. The active optocouplers each switch their signal to a terminal of the corresponding two-pole Kelvin contact. This ensures that the positive side of the current source with the positive side of the voltage measurement is connected together to the same terminal of the relay. The same applies to the negative sides. Now, as in the 2 shown, the outputs P1 and P2 connected, the terminals of the power source and the voltage measurement are connected at the appropriate place on the DUT. Thus, the interconnection for four-wire measurement is now complete. This matrix is in 2 shown in excerpts for a switching case. The corresponding optocouplers in this case are Q31 and Q81 as well as Q52 and Q112. Here are the connections of the resistor R41 for the connections of the relay and the resistor R41 for the contact resistance of a contact set of the relay which lies between the terminals.

• High impedance measurement with switching matrix

The range of high-impedance measurement is divided into three circuit parts. These are the provision of the measuring voltage for the high-ohm measurement, the switching matrix and the measuring circuit.

The measuring voltage for the high-impedance measurement is controlled by a control circuit consisting of T1 and T2 in 5 , provided. The control circuit limits the measuring current so that it is not overloaded with low-resistance insulation faults.

This output voltage is the switching matrix and a resistor combination consisting of R15 and R17 supplied to the ADC. The switching matrix switches this measuring voltage to the adapter socket. The switching matrix also couples the measuring voltage from the adapter socket and forwards it to the measuring circuit of the high-impedance measurement.

The high-ohm resistance measurement is prepared with the measuring amplifier around IC9 and performed by the ADC in the μC. With the FET Q1 and the corresponding control signal "IS256", the measuring resistor for the high-resistance measurement can be changed in a ratio of 10 to 1. The higher measuring resistor (150 kOhm) exists when the FET Q1 is not switched. The measuring amplifier IC 9 is connected as a voltage follower. The resistors R53 and R54 in conjunction with the capacitors C82 and C83 eliminate interfering signals in the measuring signal. The diodes D1 and D10 provide a voltage limitation of the measuring signal at the input of the amplifier (IC9). The diodes D2 and D3 serve to limit the voltage in the event of a fault.

• Measurement of contact resistance

• • Stromquelle der Milliohmmessung
• • Messkreis der Hochohmmessung.

In this measurement method, it is indirectly determined whether a coating is on the terminals of the relay. This essentially happens with the circuit parts:

• • Milliohm meter current source
• • High ohm measurement loop.

For this purpose, the power source is used as a constant voltage source. This voltage is now given by the switching matrix of the Milliohmmessung on the connection of the adapter socket. The switching matrix of the high-ohm measurement couples the measuring voltage to the measuring circuit of the high-impedance measurement from the second side of the Kelvin contact of the adapter socket. As in 6 is shown using the MOSFET Q2 and the resistor R51 the measuring circuit for measuring the contact resistance is set. Thus, the voltage at the output of the measuring amplifier IC9 is the measure of the contact resistance and is determined by the ADC in μC.

The table below briefly summarizes the functions of each connector. connector name function SV-X1 Control relay Control port extension Control DCDC converter Transmission of measured values SV-X4 Relay adapter coil part SV-X7 Supply for power supply KpSW SV-X8 Output of power supply KpSW SV-X9 Communication for power supply KpSW SV-X5 Relay adapter switching levels Part 1 SV-X6 Relay adapter switching levels Part 2 SV-X3 Supply from the external power supply SV-X2 Supply + 5V from the μC board

LIST OF REFERENCE NUMBERS

1

examinee

2

Schatmatrix

3

voltmeter

4

voltage measurement

5

Constant current source

6

Spannungseinpseisung

7

power adapter

8th

Opptokoppler

ICx

operational amplifiers

Qx

Field Effect Transistor

Tx

transistor

dx

diode

Rx

resistance

cx

capacitor

Claims (5)

Device for functional testing of a relay with a coil circuit for driving the relay coil and at least one switching level, characterized in that the device has a switching matrix consisting of 144 optocouplers with MOSFET outputs. Device for functional testing of relays according to Claim 1 , characterized in that different switching levels can be measured independently. Device for functional testing of relays according to one of Claims 1 and 2 , characterized in that the switching matrix is interconnected so that a four-conductor measurement is performed. Device for functional testing of relays according to one of Claims 1 to 3 , characterized in that a supply voltage in the device is adjustable. Device for functional testing of relays according to one of Claims 1 to 4 , characterized in that a switching between the measuring circuits for low-impedance measurement / high-impedance measurement is automated within the device with the switching matrix.

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