The exhaust air systems in several buildings of a university’s chemistry department urgently needed to be overhauled. Thanks to its extensive expertise in this area, the Aachen-based company Wagner & Müller came up with a compelling system concept based on Eaton’s SmartWire DT communication system and PKE motor starter combinations, and was awarded the contract. In contrast with conventional HVAC systems, the new solution relies on high-performance standard components that also offer proven cost savings.
The exhaust air systems of three chemistry buildings at a German university were due for an upgrade. Occasionally, it was not possible to open the doors because the air supply system had failed. A total of five new systems are in planning, which will become operational in several stages.
The proposed solution for the exhaust air system relies on SmartWire-DT: SmartWire-DT is the integrated communication and wiring technology from Eaton. This uniform and open system replaces the control wiring of individual components, from circuit breakers to motor starters and frequency inverters all the way to pilot devices. In total, around 500 Eaton PKE motor starters were installed in the buildings of the chemistry department, in combinations consisting of two devices, for low as well as high fan speeds. The speeds of the two motor starters are calibrated to one another, both at the hardware and software level. All the fans were installed on the roofs of the buildings, with several smaller rooms or one larger one assigned to each fan.
Each of the five exhaust air systems consists of a switchboard (2.6 metres wide, 2 metres high) that contains an Eaton HMI/PLC – a 7.4 inch XV touch panel with a Profibus DP interface – as well as DOL starters mounted on Eaton’s SASY 60i busbar system. In combination with the Eaton circuit breakers and motor-protective circuit breakers, the SASY 60i system provides an integrated, UL-certified solution for switching, controlling, protecting and distributing power.
The SmartWire-DT-connected PKE motor-starter combinations allow for easy automation of the system: The PKE-SWD-32 modular COM interface records the current flowing through the PKE devices and also provides various signalling functions such as diagnostic, status or overload messages. All process-relevant data are transferred directly to the controller and are available throughout the entire system. The resulting data transparency increases the efficiency and operational reliability of the drives in the vicinity of the motor-protective circuit breaker. This provides the PLC (or control system) with up-to-date and precise data for diagnostics, which can also be used to specify the trip and overload settings of the motor-protection system.
Müller and Wagner came up with a compelling solution based on standard components, which offer a number of benefits for the university’s chemistry department: Rather than relying on an isolated, proprietary solution, the building automation concept is based entirely on standard components. Any qualified technician can carry out maintenance work on the hardware and software, and, if necessary, expand the system as required in accordance with the applicable standards. This also applies to the XV100 HMI/PLC, which, like all xSystem product groups, is programmed using the CODESYS-based xSoft-CODESYS-2 software in accordance with IEC61131-3. The visualisation can either be implemented with Galileo or, as in this case, with CODESYS Target. The HMI/PLC of each of the five systems is backed up by an Eaton 5125 UPS.
This solution also allows the university to implement an efficient energy management system. This makes it possible to evaluate the energy consumption of each motor and to forward the data to a monitoring system for analysis.
The exhaust air system is designed in such a way that if level 2 (high speed) fails, level 1 (low speed) will take over to keep the system operational.
The result is an autonomous exhaust air system with the option of implementing a central ventilation system.
The five exhaust air systems operate independently of one another, and therefore do not require any connection to the central ventilation system in order to be operational. For now, the control level is based on the Modbus protocol and connects to BACnet via a gateway. A connection of the SmartWire-DT-based system to the central ventilation system via Profibus DP is currently being discussed. This would allow for the implementation of a centralised monitoring system, thanks to SmartWire-DT, which will also contribute towards making the solution future-proof. The SmartWire-DT cable not only makes it possible to simultaneously monitor the motor currents of all 250 dual drives, but this information can also be transmitted to the building control centre via OPC.
PKE with ZMR plug-in trip block
The PKE motor-protective circuit breakers can also be equipped with ZMR plug-in trip blocks: In the event of a motor overload, the ZMR-PKZ trip block with overload relay function will not only switch off the circuit breaker itself, but also the downstream contactor. In this way, the PKZ remains closed and does not have to be manually reset.
Robert Wagner CEO of Wagner & Müller sums up the system as follows: We presented our concept to the university’s planners, who had the required technical know-how and therefore found our proposed solution compelling. The combination of SmartWire-DT with the PKE motor starters offers the perfect solution, and not only because it saves money. SmartWire-DT increases system availability, reduces the control panel wiring and eliminates time-consuming troubleshooting during commissioning and maintenance.”