Monitoring of switchboards in a logistic warehouse

Reliability of logistics parks’ operation

Logistics parks are ideal locations for operations within “City Logistics” as well as for headquarters for medium and large companies. They facilitate the distribution of goods at the final stage, which is important for logistics operators and e-commerce companies. To maintain the uninterrupted operation of such parks, it is necessary to ensure an appropriate level of security. One of the critical points is the LV main switchgear because the power components are the most common causes of breakdowns and fires.

A key indicator of the correct operation of switchboards and the risks that may occur during their operation is the temperature inside them and at the connectors. In particular, the so-called “Hot spots” in old and new, overloaded and poorly maintained switching stations are the most sensitive. This makes the predictive supervision of newly installed switchgears and ensuring their reliable operation all the more important. Excessive temperature rise, and hence heating of “hot places”, such as terminals of main and outgoing switches, and busbar connections, increase the risk of fire, pose a threat to people in the vicinity and may cause work interruptions, which is very expensive for the operation of such facilities. Traditional control of the efficiency of switchgear operation is often performed by thermography. However, it has limitations in terms of efficiency and accuracy, resulting from the difficult visibility of some internal areas obscured by other elements or with difficult access. In addition, the infrared imaging process shows only a momentary value, which limits the assessment of the long-term correctness of the tested elements.

It is possible to eliminate these limitations by using temperature sensors that control the operation of the switchgear 24 hours a day, 7 days a week. The use of such sensors allows measurement even in the most inaccessible places. Permanent control also enables the sending of warnings and alarms as soon as a failure is detected, as well as data collection for long-term archiving and trend evaluation.

Inspection of switchgears in a logistic warehouse

Inspection of the new and properly used switchgear is just as important as the inspection of the old or neglected ones. Their failure may stop the operation of the warehouse, thus causing losses and delaying deliveries. It can also pose a threat to human health and life. To prevent such events, in the newly created logistics warehouse in Warsaw, AB-micro sp. z o.o. in cooperation with RAFAEL Security Systems Sp. z o.o. installed a continuous temperature monitoring system in the main switchboard. Exertherm EM sensors were used there.

Exertherm EM wired sensors are designed for continuous temperature monitoring at connectors, switch terminals, and rail connections. The sensor housing is made of high durability material with high mechanical resistance. It effectively protects the delicate parts of the sensor during installation and operation. Their battery-free operation allows for constant monitoring of the switchgear operation and does not require ongoing maintenance. The use of these sensors makes it possible to measure the temperature of several hundred different points at the same time, even in hard-to-reach places. To eliminate the influence of the ambient temperature on the measurement, the sensor compensates for the change in resistance between the measuring point on the cable and the point suspended in the air inside the switchgear. The result of the measurements is the temperature difference between these points.

Exertherm sensors were mounted in the logistic warehouse in the main switchboard, on each wire feeding the main switch, near its terminals.

Temperature measurement in the main switchboard

Specification of the Exertherm EM:

• Sensitivity range: -10> 150 ° C
• Accuracy: +/- 2% or 1 ° C
• Repeatability: 1 ° C
• Working temperature: 70 ° C
• Housing: PTFE UL94 V-O
• Output cord: 4 m UL-Style 2464

Remote collection of measurement data is ensured by the high-quality “Exerthem Modbus Datacard” dedicated to Exertherm 24/7 thermal monitoring systems. Data is sent via RJ45 connector to RS-485 Modbus network through sockets that can be used as inputs or outputs. A single card allows you to simultaneously receive and analyze signals from 8 different sensors. A maximum of 32 cards can be chained together, allowing 256 sensors to be used simultaneously. The use of LEDs on the front panel of the card makes it possible to observe the operating parameters of the card, the power supply status, and the functioning of Modbus communication. The card is designed to be mounted on a DIN rail and powered with 24 V DC, with a power consumption of 0.4 W.

The Exertherm Modbus Datacard converts the state and parameters of the input signal from sensors and sends them to the network. It enables communication and integration with all BMS/SCADA systems.

Information on alarms related to exceeding the set temperature thresholds is provided through the MT-151 MOBICON series telemetry module by Inventia Sp. z o.o. in two ways:

• Electric – putting a signal on the appropriate binary output and activating the relay,
• Digital – via Ethernet and Modbus TCP protocol.

It is also possible to transmit data via GSM/GPRS with the use of SIM cards installed in MT devices.

Temperature monitoring of the facility switchgear

To ensure safety in the logistics warehouse, in addition to temperature control of the main switchgear, the facility switchgear is also monitored. Its monitoring is based on the control of the air temperature inside the switchboard and the air temperature in the hall, near the place of its installation. There are two Pt1000 sensors inside the field switchboard. One of them is placed in the upper part of the switchgear, the other one in the lower part, ensuring constant control of its correct operation.

Information on alarms related to exceeding the set of temperature thresholds is transmitted by the MT-156 HMI telemetry module by electric means. In case of exceeding the alarm thresholds, appropriate signals are issued on the binary outputs. Similar to the MT-151 model, the MT-156 HMI telemetry module can transmit data via GSM/GPRS using SIM cards installed in MT devices.

Remote monitoring and control is the technology of the future

The use of temperature sensors in switchboards guarantees a much higher level of safety than in the case of periodic supervision by a man with a thermal imaging camera. The collection of data in a continuous manner allows the more precise analysis so that preventive measures can be introduced, e.g. circuit breaker service.

The main advantages of the continuous temperature control system are:

• measurement in hard-to-reach places
• accurate measurement data
• measurement of even several hundred points at the same time
• remote temperature reading on sensors
• data transmission to the monitoring system
• access to data and their analysis
• preventing failures and their consequences
• sending alarms about exceeding the preset allowable temperature value threshold to specific telephone numbers
• no need for ongoing system maintenance.

AB-micro Sp. z o.o., which implemented the system in the logistics center mentioned above, is a distributor of Exertherm sensors in Poland. We invite companies facing similar challenges to cooperate with us. We offer both the sale of sensors and the implementation of the entire system to monitor the operation and temperature of the switchgear. This project uses MT telemetry modules produced by Inventia Sp. z o.o., closely related to AB-Micro Sp. z o.o.