As a maintenance electrical engineer, I can say that electrical maintenance is interesting. I discover new things when performing proper deep maintenance for electrical equipment. For example, I had a closer look at electrical transformers from inside, I checked its iron core, tap changer, oil tank and almost every thing inside it.
I have a great team, we work together to make various types of electrical maintenance for almost all kind of electrical equipment. In this article, I will happily discuss maintenance activities and work we do in our large workshop. Let’s get started.
What is Electrical Maintenance Work?
Electrical devices can stop working, or some times maintenance is required to get desired goals. Therefore, to perform maintenance of electrical devices after a specific interval of time. To move further let’s define, what is electrical maintenance.
Electrical Maintenance is the process of testing, evaluation, monitoring, fixing, and replacing different parts of an electrical system or device.
To perform these actions, the concerned person must be equipped with hands-on knowledge. Besides this, he/ she must have valid certificates from the concerned authorities.
Different types of electrical maintenance are
- Reactive maintenance
- Preventive maintenance.
- Corrective maintenance.
- Predetermined maintenance.
- Condition-based maintenance.
- Predictive maintenance.
Electrical maintenance is required in every electrical field. However, it depends upon the electrical device or system. Which type of maintenance is required. In this article, we will discuss step by step maintenance process of Electric motors, Transformers, and Panels.
I have written a detailed article about maintenance types, you can read it here.electrical4uonline
Maintenance of Electric Motor
An electric motor is one of the most important parts of the electrical system. Every electrical system includes different types of electric motors.
While most of the electrical systems are dependent upon electric motors. If the motor stops working, the whole system will collapse.
To ensure safe and uninterrupted operation maintenance of electric motor is required periodically. Therefore, it is important to discuss the maintenance of electric motors in detail.
Three different types of maintenance checks are required in the maintenance of electric motors. This includes preventative, predictive, corrective, and reactive maintenance.
To ensure a safe and continuous operation and to prevent operational problems preventative maintenance is required. In this type of maintenance, a technician tries to discard unexpected motor stopping. For this purpose, the following tasks need to be completed.
- Checking of lubricant/oil etc. You can find the recommended interval between lubricants and the lubrication type and value on the motor nameplate. Never over/under lubricate the motor, both can harm it.
- Motor voltage and current readings. Use a separate multi-meter when measuring the voltage and current of the motor, i.e don’t rely on the meters on the motor control panel. Record the readings in the maintenance sheet.
- Motor sound. In this step, only experienced persons of your team should do this check. To be able to determine any abnormal sound. We check for bearing failure, this is the most common abnormal sound we find in motor PM.
- Ventilation, humidity, and condensation of electric motor. Make sure the cooling fan of the motor is working properly, in some cases, we find plastic bags closing the motor ventilation holes. This causes the motor to overheat. But, don’t worry, its temperature reduces as you remove the bags, and let the air flow freely.
- Checking electric motor for any type of loose connection and dust removal if there is any.
- Check the motor earthing connection. Make sure its resistance value is less than the permitted range. In many countries and applications it should be less than 5 Ohms.
To ensure that the right type of maintenance is carried predictive maintenance is carried out. In this type technicians’ certain types of electric motor checks. The purpose of these inspections is to find any problem with a motor in the early stage and to tackle the issue with less amount of damage or loss. Different steps are involved in predictive maintenance.
- Inspect the overall core of the electric motor.
- Stator and rotor condition, insulation, and grounding.
- Check the motor temperature rise, use a thermal imaging to detect it.
- Check vibration of the motor.
- Phase to phase and phase to ground high potential test in case of AC motor, medium voltage.
- In the case of DC motor High potential ground test.
- Any other type of inspection is deemed feasible by the technician.
Corrective maintenance is carried out if an issue comes up during operations. Different corrective maintenance can be taken if a motor goes into the following states. This type of maintenance depends on the daily observation and operator reporting.
- If there is an issue with motor starting: In this case please check the connection, fuses, starter circuit as well as insulation windings.
- Motor Heats Up: Whether motor ventilation is OK? Clear dust from and check the load connected with the motor.
- In case of burn smell, or smoke: Check motor ventilation, current, voltage and windings for any short circuit or moister.
Sometimes repairs and replacing of motors are mandatory in the electrical systems. For this purpose, reactive maintenance is required. If there is good preventative maintenance or predictive maintenance, the need for reactive maintenance will be less.
In reactive maintenance, faults causes are examined. If the fault occurs due to a small part, it can be repaired, otherwise, you need to change the whole electric motor.
I have written a detailed article about, how to check electric motor? you can read it here.electrical4uonline
Maintenance of Transformers
Just like motors, Transformers are also an important part of electrical systems. As transformers are hard devices having no moving parts. So, the types of maintenance involved in transformer maintenance are condition-based maintenance.
And in most cases, visual inspection is enough. Besides these, two types of transformer checking are common. One is regular checking, i.e. weekly, monthly, and annually. And the other is at the time of the problem.
Transformer maintenance includes the following steps. However, there are different types of the transformer, so the maintenance types may vary with types of transformer.
Below are some common maintenance checks, that almost all types of transformers require.
- Oil level, the oil level gauge is the tool to check the oil level in the transformer tank. Note that transformers with a conservator tank has the level gauge on the conservator side, the normal level is about the mid of the tank, i.e not the top of the tank. This is because the oil breathing in and out process needs a room for oil expansion.
- Leakage if any exists. Clean any oily parts of the transformer body, let it 24 hours and check it again. If any oil leakage appears again, then repair it. We do so, because in some cases a temporary leakage happens in case of new transformers during transformation and installation. We need to be sure of the leakage before doing into any maintenance.
- Check transformer bushes for cracks , breaks and dust accumulation. We use water live cleaning to clean critical OHTL parts and transformers. For more information about OHTL live maintenance read my article here.
- Ventilation of transformer, make sure the cooling radiator pipes and sectors are free of foreign objects like birds nests. Make sure all fans and oil pumps are working as required.
- Connected load in some cases if the transformer does sparking or trips.
Maintenance of electrical control or distribution panels
Electrical control or distribution, is a box consisting of circuit breakers and other electricity-related components. The purpose of this panel is to control and protect different appliances from overcurrent and other faults.
Panels are installed everywhere including residential, industrial, and health care centers, where the distribution of power is required the size and equipment installed in the panel varies with the type of location.
For example, residential locations like homes, apartments need a small box as compared to factories and industrial-purpose panels. As lights, and another electrical appliance are connected to it.
Sometimes due to dust, humidity, or loose connection panel setting distorts. And there is a risk of electric shock or another related hazards. Therefore, proper preventative maintenance is required for it.
In my work, the heavy rains are common in the winter season, we faced some panels issues when the rain enters into the panel. The main reason of this is that the panel is not sealed properly.
We make visual inspection for all panels before the winter season, to avoid such faults. We close any unused openings and make sure that all cables enter the panel using a suitable fittings.
Steps include in preventative maintenance of panels:
- Perform a visual inspection of the interior as well as the exterior of the panel.
- Remove dust, if there is any. Use a vacuum cleaner, don’t use an air blower. Blower just spreads the dust inside the panel and make it penetrate contacts and terminals.
- Check wiring, relays, breakers, contactors, timers, and other power supply units. Whether they are in working condition or not.
- Whether rated fuse installed and in working condition or not
- Check for any loose connection. its better to re-tighten all contacts and terminals.
- Check for any type of sparking and overheating. I use a thermal imaging camera to detect all hot spots, a hot spot means one of two things, a loosen connection or an overload. Remember to do thermal imaging only while the panel is live and loads are on. Because if the loads are off, no heat will be detected. (no current, no heat).
- In the case of industrial location, check for power meters, sensors, indicating lights and warning lights.
- Whether over current and overvoltage devices work properly and are rated according to the system or not.
- In the case of the health care area, follow up complete safety guide as per required checklist.
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