Patent Description:
As required by regulations, the maintenance of MV/MV and MV/LV electrical substations is aimed at ensuring high reliability in terms of prompt detection of faults, failure prevention and functional monitoring.

The objective of a maintenance operation is to maintain the performance of a system unchanged over time.

There are basically two types of maintenance: preventive maintenance according to CEI <NUM>-<NUM> and CEI <NUM>-<NUM> and predictive maintenance according to UNI <NUM>. Both types of maintenance require monitoring the electrical operating parameters and the environmental conditions, such as substation temperature and humidity, as well as cleanness.

It is the object of the present invention to provide a simple and compact environmental parameter monitoring system that allows maintenance operations on electrical panels and substations to be carried out efficiently and reliably.

Patent document <CIT> discloses a power distribution box for construction sites provided with environmental parameters sensors and means for transmitting the collected data remotely.

Patent document <CIT> discloses a system for monitoring environmental parameters of enclosures of power and communication units.

Patent document <CIT> discloses examples of dust accumulation monitors.

Patent document <CIT> discloses a distribution box provided with a removable ceiling and with sensors to detect when doors are open.

The invention achieves the object with a monitoring system of electrical substations according to claim <NUM>.

Specifically, the dust sensor comprises a photo-transmitter for light emission and a photo-receiver which collects light as reflected by the transparent wall.

The probe comprises temperature, humidity and dust sensors integrated with a single sensor device which can be interfaced with the control unit of an electrical substation monitoring system according to the invention.

Further objects, features and advantages of the present invention will be more apparent from the following detailed description provided by way of non-limiting example and illustrated in the accompanying figures, in which:.

The following description of exemplifying embodiments refers to the attached drawings. The same reference numbers in the various drawings identify the same elements or similar elements. The following detailed description does not limit the invention.

With reference to the block chart in <FIG>, an electrical substation monitoring system according to an embodiment of the invention comprises a control unit <NUM> interfaced with a plurality of sensors. Such sensors include environmental sensors, including at least a dust sensor <NUM>, a temperature sensor <NUM> and a humidity sensor <NUM>, also collectively named TPU in the present description, and relay contacts <NUM> to detect when a substation door is open. The environmental sensors may be independently interfaced with control unit <NUM>, but in a preferred configuration they are arranged inside a probe <NUM> interfaced with the control unit <NUM> through bus communication, as shown in the figure.

The control unit <NUM> is a typical microcontroller or microprocessor device <NUM> provided with program memory <NUM> and input devices <NUM> towards the sensors, output devices <NUM> towards alarm and/or actuating devices <NUM> and towards a graphic and/or communication interface with a remote control unit <NUM> of the substation. The control unit <NUM> can thus integrate the operating information of the transformers in the substation with environmental information for complete monitoring. For example, as we will see in detail below, the alarm/actuating devices may comprise fans, heaters and light signals.

By virtue of the control unit and the TPU sensors, it is possible to monitor temperature, dust deposit, humidity and, in an improved embodiment, also the opening of the doors (door1 and door2) of the electrical substation, thereby creating a useful tool to program and manage system maintenance.

<FIG> shows a different schematization of the control unit <NUM> with the following components highlighted:.

Then there are further outputs (not shown in <FIG>) to send alarm or actuation commands to motor-driven fans BLDC to extract air from the substation and to heaters.

In this configuration, the sensor probe <NUM> is configured to accommodate one or more dust sensors, while possible temperature and/or humidity sensors are interfaced with the control unit through dedicated ports. In a particularly advantageous embodiment, the temperature and humidity sensors are also integrated with the sensor probe <NUM> and communicate through the i-Bus itself to create a very compact and efficient device.

More specifically, the control unit <NUM> allows the management of the substation environment as regards:.

The substation environment is typically considered optimal for parameter values in the following ranges:.

The control unit <NUM> may advantageously display a connection for remote monitoring, via RS485 serial, Ethernet or wireless communication and outputs for activation of commands or signals, specifically:.

The control unit <NUM> has advantageous digital and power link connections and can be easily installed on a bracket, optional, for wall mounting. It has a power supply range of <NUM>-260Vac <NUM>/<NUM> and compact dimensions for DIN rail installation. The data exchange protocol is typically based on a bus with two data cables and two power cables.

The control unit may assume various configurations as a function of the type and number of input/output ports. Some examples are given below.

The following are present in a first configuration:.

The alarms relating to the various monitored parameters and the various data inputs are preferably managed and programmed as described below:.

The alarms related to the temperature parameter THi can be programmed with a range from <NUM>° C to <NUM>° C, with <NUM>° C steps. The parameter THi can be enabled "YES" disabled "NO". With NO programming, the parameter THi is not considered; with YES programming it is as follows:
When the sensor detects a temperature <NUM> higher than the value set as the limit of THi, after about <NUM> seconds, the relays switch and the alarm LEDs associated with the parameter THi turn on during programming, i.e.:.

The alarms related to the temperature parameter TLo can be programmed with a range from -<NUM>° C to <NUM>° C, with <NUM>° C steps. The parameter TLo can be enabled "YES" disabled "NO". With NO programming, the parameter TLo is not considered; with YES programming it is as follows:
When the sensor detects a temperature <NUM> lower than the value set as the limit of TLo, after about <NUM> seconds, the relays switch and the alarm LEDs associated with the parameter TLo turn on during programming, i.e.:.

The alarms related to the humidity parameter rH can be programmed with a range from <NUM> to <NUM>%RH, with <NUM>% steps. The parameter rH can be enabled "YES" disabled "NO". With NO programming, the parameter rH is not considered; with YES programming it is as follows:
When the sensor detects a temperature <NUM>% higher than the value set as the limit of rH, after about <NUM> seconds, the relays switch and the alarm LEDs associated with the parameter rH turn on during programming, i.e.:.

As soon as the detected humidity returns to values either equal or lower than the set limit, the relays switch and the LEDs turn off (FAN/HEATER-ALARM).

The alarms related to the dust parameter dSt can be programmed with a range, e.g. from <NUM> to <NUM> dSt, with <NUM> dSt steps. Of course, other values can also be considered based on market requirements. The parameter dSt can be enabled "YES" disabled "NO". With NO programming, the parameter dSt is not considered; with YES programming it is as follows:
When the sensor detects a value higher than <NUM> dSt with respect to the value set as the limit dSt, e.g. after about <NUM> seconds (or for different threshold values according to the application needs), the relay switches and the LED associated with the parameter dSt turns on during programming, i.e.:.

As soon as the detected dustiness conditions return to values either equal to or lower than the set limit, the relays switch and the LEDs turn off (ALARM). It is suggested to clean the substation in case of DST ALARM.

The control unit has two entrance doors D1 and D2, Door <NUM> - Door <NUM> connections. Enabling inputs D1 and D2 can be used to monitor the status of the door contacts (NC).

With the enabled parameter, D1 or D2 YES, the opening of the connected contact is followed, after about <NUM> seconds, by the switching of the relay and the turning on of the LED associated with parameter D1/D2 during programming, i.e.:.

The control unit <NUM> can have optional outputs for real-time remote monitoring for acquiring values and managing all alarms. These outputs comprise:.

The integrated module includes all essential network features, such as a 10Base T / 100Base-TX Ethernet connection, complete TCP / IP stack, suitable for working as a Modbus TCP slave.

As far as sensors are concerned, a particularly advantageous embodiment provides the use of a single component which integrates several environmental sensors in it, as shown in <FIG>. For this purpose, a container <NUM> with transparent lid <NUM> is used, which accommodates a temperature sensor <NUM>, a humidity sensor <NUM> and a dust sensor <NUM> interfaced to a unit for bus communication with the control unit <NUM>. The probe <NUM> may also contain only one of said sensors or several sensors of the same or different types in any combination.

Although the temperature sensor <NUM> and humidity sensor <NUM> may be purchased components, such as an L23EM1A humidistat, spiral capillaries such as those used in C10 room thermostats, dust sensors cannot be purchased. Indeed, the only particulate matter detectors for monitoring air quality on the market are not suited for this purpose. For this reason, the dust sensor was completely developed by virtue of an original idea of the inventors based on the following observation. When dust accumulates on a transparent surface, the light passing through such surface is reduced, i.e. the dust acts by varying the transparency of the surface. Hence the idea of using an optical detector inside a container with a transparent wall. By detecting the amount of light which can reach the sensor, it is possible to estimate the opacification effect of the transparent surface due to the possible presence of dust. For this purpose, the transparent wall must be the one which, when installed in the substation, remains in a horizontal position to accumulate as much dust as possible. According to the invention, it is the lid of a container so that it can also be easily cleaned. In one respect, the invention requires the use of a container <NUM>, e.g. RND <NUM>-<NUM> with transparent lid601, like the one shown in <FIG> in which an optical sensor <NUM> is housed.

SHARP manufacturer produces some sensors with analog output equipped with a system consisting of an IR transmitter and a photo-receiver, such as the GP2Y1014AU0F. This type of sensor is used to control the air quality of air conditioning systems. The mechanics are designed to measure the air flowing in a duct and not that present in the environment.

The sensor can measure the density of dust in the air and produce a proportional DC voltage on a scale which is difficult to use for this application.

The control circuits of the LED and receiver are external and are quite critical in particular for degradation over time. This sensor is, therefore, usable but not optimal. Other sensors use laser technology with an integrated fan.

These sensors offer the advantage of increased selectivity from <NUM> to <NUM>. They are provided with an internal controller capable of identifying the concentration of particles as a function of dimensions.

These products are too sophisticated for the application discussed here, but they are equally usable.

The manufacturer OMRON recently introduced a PWM output dust sensor, the B5W-LD0101-<NUM>/<NUM>, with specific mechanics for monitoring environmental air quality. By heating a resistor, it produces a slow flow of air in a dedicated duct and counts the dust particles present.

The electronics to drive the TX and RX elements are integrated with the sensor and the output produces a series of pulses according to the amount of dust detected.

It is thus possible to know how much air is circulating over time, which is the information needed to signal the need for early maintenance. This type of sensors has proved to be the most suitable to make a device capable of determining the accumulation of dust in an electrical substation, even if obviously optical sensors of any type can be used for this purpose.

The EESB5-B model made by the manufacturer OMRON shown in <FIG> is a sensor which can be arranged inside a container with a transparent lid to measure the accumulation of dust. Indeed, it is a sort of optical proximity switch that the inventors have transformed into a surface deposit dust sensor.

The purpose is to signal an excessive dust deposit on a flat surface. When the sensor is mounted in contact on a transparent flat surface about <NUM> thick, it produces a direct voltage which is directly proportional to the level of dirt deposited on the surface to be controlled. The inventors have made some tests with substances of different granularity and characteristics such as flour (a), breadcrumbs (b), coffee powder (c), dry soil (d) under conditions of low, medium and abundant deposit on the surface, as shown in <FIG>, inserting three sensors E1, E2, E3 in an RND <NUM>-<NUM> container with transparent lid as shown in <FIG>, connecting them to a +<NUM> V power supply and taking the output voltage (V) on a <NUM> kΩ emitter resistor. The tables of the results obtained as shown below.

Signal measurement in the presence of flour.

The flour powder is very fine and clear, so the level of reflection is very high.

Signal measurement in the presence of ground coffee.

Ground coffee is quite coarse and dark, so the level of reflection is lower.

Signal measurement in the presence of breadcrumbs.

Breadcrumbs are also quite coarse and dark, so the level of reflection is lower.

Signal measurement in the presence of dry soil.

Dry soil powder used has a fine and medium graininess and an intermediate color shade.

As can be seen from the tables, the device according to the invention has such a sensitivity that it can be used to detect the presence of dust, e.g. in an electrical substation.

In this regard, a further example relates to a probe <NUM> for measuring dust in a room comprising a container <NUM> with a transparent wall <NUM> and an optical sensor <NUM> coupled to the transparent wall to detect the passage of light through said wall. The sensor, in its simplest embodiment shown in <FIG>, comprises a photo-diode for the emission of light and a photo-transistor which collects the light emitted as reflected by an object placed along an optical axis, specifically the transparent wall of the container.

Turning back to the system as a whole, the control unit <NUM> is configured to communicate with the environmental dust <NUM>, temperature <NUM> and humidity <NUM> sensors. The same container used to make the dust sensor <NUM> as seen above is used to accommodate the temperature sensor <NUM> and the humidity sensor <NUM>, thereby making a very compact probe typically interfaced with the control unit <NUM> through a bus e.g. power link type. The transparent wall of the container is advantageously closed so that it is easy to clean.

Claim 1:
An electrical substation monitoring system comprising:
a probe (<NUM>) adapted to detect environmental parameters within an electrical substation;
one or more relay contacts (<NUM>) capable of detecting the closing of one or more doors of the electrical substation;
a control unit (<NUM>) in communication with said probe (<NUM>) and with said one or more relay contacts (<NUM>), programmed to read the information coming from said probe and said one or more relay contacts (<NUM>), process said information and output the values of the detected environmental parameters to a signaling interface with possible activation of alarms and/or drives if predetermined thresholds are exceeded wherein the control unit is configured to activate an alarm signal when at least one of said one or more doors is open,
wherein said probe (<NUM>) comprises at least one dust sensor (<NUM>), adapted to detect the amount of dust which is deposited on a flat surface, a temperature sensor (<NUM>) and a humidity sensor (<NUM>) integrated, and
wherein the probe (<NUM>) comprises a container (<NUM>) with a bottom wall (<NUM>) intended to rest on a horizontal surface in the substation and a transparent wall (<NUM>) parallel to said bottom wall (<NUM>), the bottom wall supporting the temperature sensor (<NUM>), the humidity sensor (<NUM>) and the dust sensor (<NUM>) wherein the dust sensor is an optical sensor (<NUM>) with optical axis facing towards the transparent lid (<NUM>) to detect the light reflected by said transparent lid (<NUM>) which functions as said flat surface.