Pump for wastewater applications and / or a water supply

Abstract

Pump (1) for wastewater applications and / or a water supply with a pump housing (2) and a motor (3) and a motor protection device (4) connected to the pump (1), wherein the motor protection device (4) provides a conductivity sensor (7) and a protection relay (5) with a microprocessor (6) which is connected to the conductivity sensor (7) for evaluating an output signal of the conductivity sensor (7), and at least one further sensor (8-11) is connected to the microprocessor (8).characterized in that the microprocessor (6) is galvanically connected to a ground potential of the pump housing (2) and the conductivity sensor (7) has a first contact galvanically connected to the pump housing (2), which is connected to the microprocessor via a first line (14b) and the conductivity sensor (7) has a second contact that is galvanically isolated from the pump housing (2) and is connected to the microprocessor (6) via a second line (14a).

Description

[0001] The invention relates to pumps used in water supply or wastewater applications.

[0002] Such pumps represent valuable capital goods with high procurement costs and long replacement times. Therefore, it is desirable to protect these machines from damage caused by critical operating conditions, incorrect operation, or overload. State-of-the-art protective relays from factory automation are often used for this purpose. These relays monitor, for example, the motor winding temperature, the bearing temperature, or leakage in the pump. Separate protective relays are used for each of these measured values.

[0003] US 2015 / 0226220 A1 discloses a pumping system with a leakage detection system that includes a conductivity sensor connected to a control unit for activating a relay. Furthermore, additional sensors can be provided in the pumping system.

[0004] Other pump systems with leakage detection systems that incorporate a conductivity sensor are known from US 2004 / 0265154 A1 and US 2004 / 0105758 A1. US 2014 / 0255215 A1 describes a method for monitoring and controlling a pump using multiple monitoring sensors.

[0005] EP 2 725 691 A1 relates to an electrical motor vehicle accessory unit with an engine electronics board which has a circuit ground island which is connected to a vehicle ground island via an EMC filter element and further provides a housing ground island which is also connected to the vehicle ground via the vehicle ground island via an EMC filter element.

[0006] Furthermore, US 5 188 143 A discloses a conductivity sensor whose electrodes are connected to each other via a low-voltage battery and a signal generator.

[0007] In practice, false alarms caused by EMC interference repeatedly occur when protecting pumps. These cause the pumps to shut down without any actual fault, disrupting the water supply and disposal infrastructure. Furthermore, unnecessary costs arise for water utility operators because service technicians have to investigate the fault reports.

[0008] The invention is therefore based on the object of increasing the reliability of pump protection and at the same time enabling complete monitoring of the pump for various parameters.

[0009] According to the invention, this object is achieved by the features of claim 1.

[0010] The pump according to the invention comprises a pump housing and a motor, as well as a motor protection device connected to the pump, wherein the motor protection device provides a conductivity sensor, and a first contact of the conductivity sensor is galvanically connected to the pump housing. Furthermore, the motor protection device comprises a protective relay with a microprocessor, which is connected to the conductivity sensor for evaluating an output signal of the conductivity sensor, wherein the microprocessor is galvanically connected to a ground potential of the pump housing, and at least one further sensor is connected to the microprocessor. The microprocessor is galvanically connected to a ground potential of the pump housing, and the conductivity sensor has a first contact galvanically connected to the pump housing, which first contact is connected to the microprocessor via a first line.The conductivity sensor has a second contact that is galvanically isolated from the pump housing and connected to the microprocessor via a second line.

[0011] In contrast to the use of separate microprocessors for each sensor, the invention proposes that at least the conductivity sensor and at least one other sensor, but preferably all sensors, be connected to a common microprocessor. While it is already known in practice that protective relays have inputs for multiple sensors, these are temperature sensors that are not galvanically coupled to the pump housing. However, according to the invention, a conductivity sensor is to be used, which is used, for example, for level or leakage measurement, and whose first contact is galvanically connected to the pump housing.

[0012] In the current state of the art, each sensor is connected to its own protective relay, which in turn has its own microprocessor and power supply. This can lead to galvanic coupling between the normally separate measuring circuits. Furthermore, potential differences can arise at the different power supplies, which, due to the common potential point on the pump, can lead to compensating currents between the various protective relays. These compensating currents can be responsible for some of the false alarms. By using a common microprocessor for the conductivity sensor and at least one other sensor, the problem of potential differences and the resulting disruptive compensating currents can be reduced.

[0013] Further embodiments of the invention are the subject of the subclaims.

[0014] The conductivity sensor can be used as a level sensor to prevent the pump from running dry. The conductivity sensor can also be used as a leak sensor, for example, to monitor water ingress into certain areas of the pump.

[0015] According to a preferred embodiment of the invention, the conductivity sensor is based on an ohmic resistance measurement. The at least one further sensor connected to the microprocessor can be formed, for example, by an acceleration sensor for measuring vibrations of a pump bearing. The acceleration sensor can have a housing that is galvanically connected to the first contact of the conductivity sensor. Furthermore, the acceleration sensor can have a measuring line that is galvanically isolated from the pump housing and connected to the microprocessor.

[0016] However, the further sensor can also be formed, for example, by a bearing temperature sensor for measuring the temperature of at least one bearing of the pump, wherein it is also conceivable here that the housing of the bearing temperature sensor is galvanically connected to the first contact of the conductivity sensor.

[0017] According to a further embodiment of the invention, the additional sensor can also be a winding temperature sensor for measuring the temperature of a motor winding. The motor winding can be designed as a tooth-wound coil with a plurality of slots. It is advantageous if the two connecting leads of the winding temperature sensor are arranged in one and the same slot, since arranging the connecting leads in different slots can lead to EMC interference due to potential differences.

[0018] Furthermore, it is possible for the additional sensor to be a phase monitoring sensor for measuring the phases of a power supply used for the motor. Here, too, it is possible for the phase monitoring sensor to be connected galvanically and / or inductively via a power supply network to the first contact of the conductivity sensor. In addition to the conductivity sensor, one or more, preferably all, of the additional sensors mentioned above can be connected to the microprocessor. Of course, it is also conceivable for sensors to be connected to the shared microprocessor that monitor other parameters not explicitly mentioned above.

[0019] According to a further embodiment of the invention, it is provided that the motor protection device has a power supply connected to the microprocessor in order to provide the measuring voltages required for the sensors.

[0020] According to a preferred embodiment of the invention, the pump is a centrifugal pump or an eccentric pump.

[0021] Further embodiments and advantages of the invention are explained in the following description of an embodiment in conjunction with the drawing.

[0022] In the drawing show Fig. 1 a block diagram of the pump according to the invention with a motor protection device and Fig. 2 a circuit diagram of the motor protection device.

[0023] At the Fig. The pump 1 shown in Figure 1 is, for example, a centrifugal pump or an eccentric pump used in water supply or wastewater applications. It has a pump housing 2 and a motor 3 arranged within the pump housing 2. Furthermore, the pump 1 is connected to a motor protection device 4, which has a protective relay 5 with a microprocessor 6. Furthermore, the motor protection device provides various sensors connected to the protective relay 5 or the microprocessor 6, namely a conductivity sensor 7, an acceleration sensor 8, a bearing temperature sensor 9, and a winding temperature sensor 10. Furthermore, a phase monitoring sensor 11, for example, can be connected, which is provided for measuring the phases of a voltage supply 12 used for the motor 3.

[0024] The motor protection device 4 further includes a power supply 13 located in the protective relay 5 and connected to the microprocessor 6. The various sensors 7-11 are connected to the protective relay 5 and the microprocessor 6 via lines 14-18. Reference numeral 19 also represents an operator interface, which forms an interface between the motor protection device 4 and the operating personnel. This can be used, for example, to visualize data, particularly alarm signals from the protective relay 5.

[0025] Fig.Figure 2 shows the circuit diagram between the sensors and the microprocessor 6, here using the conductivity sensor 7 and the acceleration sensor 8 as examples. The pump housing 2 is at a ground potential 20, which is usually formed by the earth potential. The conductivity sensor 7 has a pin 7a that is insulated from the pump housing 2 and is connected to the microprocessor 6 via a second line 14a. The input circuit for the input of the microprocessor 6 is represented here as an example by a series resistor 21 and a low-pass filter formed from a resistor 22 and a capacitor 23. The isolated pin 7a represents the second contact of the conductivity sensor 7. The other, first contact of the conductivity sensor 7 is galvanically connected to the pump housing 2 and is connected to the microprocessor 6 via a first line 14b.

[0026] The acceleration sensor 8 is used to measure vibrations of a bearing 24 (e.g., a ball bearing) in the pump 1. The exemplary input circuitry in the microprocessor 6 is designed analogously to the conductivity sensor 7. The ground line 15b of the acceleration sensor 8 is connected to a metal housing of the acceleration sensor and is thus also at ground potential 20. A measuring line 15a, however, enters the acceleration sensor 8 in an insulated manner.

Claims

[1] Pump (1) for waste water applications and / or a water supply with a pump housing (2) and a motor (3) and a motor protection device (4) connected to the pump (1), wherein the motor protection device (4) provides a conductivity sensor (7) and a protective relay (5) with a microprocessor (6) which is connected to the conductivity sensor (7) for evaluating an output signal of the conductivity sensor (7), and at least one further sensor (8-11) is connected to the microprocessor (8). characterized bythat the microprocessor (6) is galvanically connected to a ground potential of the pump housing (2) and the conductivity sensor (7) has a first contact which is galvanically connected to the pump housing (2) and is connected to the microprocessor via a first line (14b), and the conductivity sensor (7) has a second contact which is galvanically insulated from the pump housing (2) and is connected to the microprocessor (6) via a second line (14a). [2] Pump (1) according to claim 1, characterized by that the conductivity sensor (7) is based on an ohmic resistance measurement. [3] Pump (1) according to claim 1, characterized by that the further sensor is formed by an acceleration sensor (8) for measuring vibrations of a bearing (24) of the pump (2). [4] Pump (1) according to claim 3, characterized bythat the acceleration sensor (8) has a housing which is galvanically connected to the first contact of the conductivity sensor (7). [5] Pump (1) according to claim 4, characterized by that the acceleration sensor (8) has a measuring line (15a) which is galvanically insulated from the pump housing (2) and connected to the microprocessor (6). [6] Pump (1) according to claim 1, characterized by that the further sensor is formed by a bearing temperature sensor (9) for measuring the temperature of at least one bearing of the pump (1). [7] Pump (1) according to claim 6, characterized by that a housing of the bearing temperature sensor (9) is galvanically connected to the first contact of the conductivity sensor (7). [8] Pump (1) according to claim 1, characterized by that the further sensor is formed by a winding temperature sensor (10) for measuring the temperature of a winding of the motor (3). [9] Pump (1) according to claim 8, characterized by that the winding of the motor (3) is designed as a tooth coil winding with a plurality of slots and the winding temperature sensor has two connecting wires which are arranged in the same slot. [10] Pump (1) according to claim 1, characterized by that the further sensor is formed by a phase monitoring sensor (11) for measuring the phases of a voltage supply (12) used for the motor. [11] Pump (1) according to claim 9, characterized by that the phase monitoring sensor (11) is connected galvanically and / or inductively via a supply network to the first contact of the conductivity sensor (7). [12] Pump (1) according to claim 1, characterized by that the motor protection device (4) has a power supply (13) connected to the microprocessor (6). [13] Pump (1) according to claim 1, characterized by that the pump (1) is a centrifugal pump or an eccentric pump.

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