IoT and Predictive Maintenance - Make Your Buildings Energy Efficient
IoT enabled predictive maintenance strategies apart from preventing unexpected equipment failures can also improve the energy efficiency quotient when applied at certain specific areas. This article highlights few such specific areas in a typical commercial building.
1: Chiller Condenser Fouling
A chiller condenser circuit is the one where the heat from the refrigerant is being rejected into the atmosphere through cold water from the cooling tower. This is an open-loop circuit and there are very high chances for deposits of soft organics or hard minerals like iron, manganese, or calcium carbonate (calcite) to happen. This will clog the condenser tubes in the long run. These minerals even will form a hard layer inside condenser tubes which reduces the effective functioning of a condenser. A well-maintained condenser always helps in elevating the performance of a chiller by reducing the lift on a compressor.
Generally, in the majority of buildings, these condenser systems are manually cleaned based on fixed scheduled maintenance periods. Quality of water and operation schedules are dynamic in nature and hence the cleaning schedule cannot be a fixed one. A 0.8 mm scale build-up on condenser tubes can increase the energy consumption of chillers by around 20% - 35%. So the time-based maintenance schedule results in loss of energy and at the same time condenser getting corroded away.
A condenser approach temperature is a difference between liquid refrigerant temperature as measured on the liquid line, and leaving condenser water temperature. Generally, the condenser approach for a water-cooled chiller will be in the range of 0 to 4 degrees. In case of any increase in this condenser approach, then it's a direct indication of fouling in a condenser. A simple IoT module that measures these temperatures continuously and triggers an alarm signal to the respective maintenance team whenever the limits are crossed can address the issues related to condenser fouling easily.
2: Voltage Optimisation
Supplying a perfect voltage always keeps equipment healthy. Generally, all major 3 phase equipment is rated for certain voltage levels around 395 to 415 V. When these equipment are fed with unnecessary higher voltages either voluntarily or due to some system fault or due to rise in supply voltage itself, causes higher magnetisation losses than normal. Especially when the equipment is underloaded then the quantum of these losses are huge. Higher voltages even lead to equipment failures. As per industry experience, there will be around a 1% increase in energy consumption for every 4% increase in supply voltage. So the supply voltage has to be monitored at all times for any minor increase in its magnitude using an IOT module that can record the frequency of occurrence of the event and can alert the respective team for corrective actions. These patterns help in understanding the exact reason for over-voltage occurrences and help in resolving the issue at a faster pace.
3: AHU Filter Monitoring
Air handling units are equipped with filters to provide required healthy ventilation inside the conditioned space. These filters get choked and need treatment or sometimes replacement for getting optimum performance out of an AHU. Every filter is designed with a certain pressure drop value thatserves as an indicator for choking. When a filter gets choked and when got unnoticed by the maintenance personnel that may result in higher pressure drops across it increasing the blower motors power consumption. This also may lead to unnecessary overloading on the blower
Generally, these filters are cleaned manually again at some prefixed intervals or when maintenance personnel observes a low CFM delivery from the unit. There will be few instances where the life of the filter might have reached its end of life and cannot perform even after cleaning. In those instances, once the maintenance is carried away then the choked filter suffers till the next maintenance schedule. A simple IoT module that senses and monitors the pressure difference across the filter continuously and compares with the designed value can better alert the maintenance personnel to act upon it and save huge amounts of energy. Even after the cleaning, immediately if such out of limit pressure drop is sensed then it can trigger an alert to replace the filter that helps the maintenance team in planning for a smart procurement of spare filters before breakdown occurs.
4: Transformer Loading Optimisation
Distribution transformers are important assets in any building that requires utmost attention in terms of their reliable functioning. Any outage can lead to a complete blackout of respective sections served by them. Distribution transformers have certain maximum efficiency loading points associated. A good amount of energy losses will be observed if this equipment operates at said non-optimal loading points. Also, a continuous overloading zone operation may trigger degradation of equipment life in the long run.
(Generally, a typical distribution transformer is efficient in 40 – 60% range) Continuous monitoring of loading vs %age energy losses between input and output can provide better insights on how to regulate the demands accordingly to operate the equipment at optimum points. And in some cases, if the energy losses are very high than normal then a simple surface temperature variation for the same can predict even the insulation degradation or other parameters effectively.
5: UPS Battery Management
Batteries are fundamental components of a UPS, which are designed to provide immediate emergency backup power. The role of UPS is incredibly essential in many commercial buildings, including healthcare and data centres, and battery failure is the leading culprit behind the majority of UPS catastrophes. UPS batteries generally have a lifespan of three to five years, which means that their ability to store and deliver power slowly deteriorates over time.
These battery packs need to be monitored for parameters like temperature rise, discharge voltage levels and float voltage levels that decide both degradation levels and performance levels of batteries. A periodic check may be effective but due to seasonal variations and load variations an IOT enabled continuous monitoring system with a programmed alarm triggering facility can provide best results.