Frequently Asked Questions:
About NewElec
About the Company
What experience does NewElec have in the field of motor protection?
The Company was established in 1978 and, at the time of writing, has delivered over 200,000 motor protection relays to the South African market alone. By virtue of the fact that the company continues to thrive in this very specific niche market despite competition from much larger international companies bears testimony to the quality of its products. Modern developments have accentuated a need for automation and control of plants. In this respect the company has and continues to embark on research and development so that its modern range of relays offers an all-encompassing solution to protection, control and automation of large plants.
Do you cater for the needs of the automation and process control industry?
Very much so. We are very aware that modern trends are emphasised by the need for control, protection and even management of plants to go hand in hand when designing fully automated plants. For this reason we have designed our products to facilitate these requirements and have made it possible to accommodate a number of popular communications protocols such as Profibus DP, Modbus RTU and Canbus. We can also communicate via Device Net. Other communications protocols are being developed as ongoing projects. The main point being that our prospective customers must never feel locked in to any specific make of PLC usage. Present designs also permit and facilitate firmware software revisions to be down loaded on-site so that our customers can continuously benefit from any new software revisions that are made. In this way they are not burdened by having to purchase new relays in order to keep up with the latest protection features / benefits.
Do you design and manufacture electronic motor protection relays yourselves or do you import such products?
We are pleased and very proud to say all products are designed and manufactured by NewElec.
Do you service your range of products?
Naturally. In fact we service and/or repair our products at a fixed price amounting to 30 % of their current list price irrespective of the age or nature of the fault(s). In doing so, we also renew the original product guarantee. See also our general terms and conditions of sale with specific reference to service and guarantee of our products.
Could you mention some companies or corporations for whom you are supplying motor protection relays?
This is both easy and difficult to answer:
There is no general industry out there to whom we have not supplied our motor protection relays. But in a more recent and modern context we can name Kumba Resources, Portnet, Columbus Stainless Steel, Umgeni Water, South Witbank Colliery, Douglas Colliery, Joy Mining Machinery, FFE Buffalo Minerals, Optimum Colliery and PFG Building Glass as good referral sources. We also design and supply motor protection relays for specific companies and under their own names if volumes are indicated.
Do you comply with any manufacturing process standard?
Yes. To ensure quality management and manufacture of products we comply with ISO 9001. At the same time our products are designed to comply with European IEC specifications both in terms of protection as well as ISOLATION, IMPULSE WITHSTAND, ELECTROMAGNETIC INTERFERENCE and HIGH FREQUENCY DISTURBANCE requirements. More recently, all our PC boards are also conformance coated to assure the utmost resilience to chemical and corrosive atmospheres.
Are your products SABS approved?
No. We prefer to have our products tested by Eskom who are also critical users of our products. Test certification from Eskom relating to any of our products is available to anyone requesting them. This does not mean we never intend to make use of the services of the SABS and is an issue open for discussion. However, in the interim, we consider the needs of our valued customers best served by the South African electricity supplier, as they are very demanding in their own selection of protection products.
Does your company export any of its products?
Yes. However this has mostly been as a result of initiatives derived by our own customers who have included our products within OEM built equipment such as crane controllers or motor control centres. In the past we have had some success in introducing our products via a distributor in Zimbabwe. As a result of these efforts we are aware that our products are in use in China, Chile, Congo, Zambia, Mauritius, Tanzania and Botswana. We are nonetheless very interested in exporting our products to any country but primarily into Africa and would welcome all trade inquiries in this regard.
Do you provide training for your product range?
Yes. We provide training for your staff on any of our products. We prefer that these training sessions take place at our own factory. It is possible to accommodate up to 8 individuals at the same time. However, for client convenience, we also offer such training at the customer selected site and arranged times and date. Presently, we do not charge for training but it is envisaged that some charge will be levied for such training in the future to cover costs only.
Why Choose NewElec
NewElec offers state-of-the-art electrical solutions tailored to meet your specific needs across various industries. Our advanced motor protection relays, dewatering pump relays, and integration-ready solutions not only enhance operational efficiency but also provide valuable insights into motor health and performance.
About Protection Terms and Basic Settings - Common Questions
Establish the current transformer ratio being used. For the purpose of illustration let us consider 3 examples.
Example 1
The motor full load is 82 Amp. The current transformers are 150:1. Simply divide your motor full load current by the primary side of your CT ratio selection and multiply by 100. In this case: 82/150 X 100= 54.6 % or 55%.
Example 2
The motor full load is 177 Amp and the current transformer ratio is 200:5. Simply divide your motor full load current by the primary side of your CT ratio selection and multiply by 100. In this case: 177/200 X 100= 88.5 % or 89 %.
Example 3
The motor full load is 210 Amp and the current transformer ratio is 200:1. Simply divide your motor full load current by the primary side of your CT ratio selection and multiply by 100. In this case: 210/200 X 100= 105%.
Where exactly do I place the external phase current sensing transformers or, in the case of relays incorporating built-in current transformers, the actual relays?
Always install the current sensing transformers or the chassis mounted relays incorporating integral current transformers in the MAIN lines to the motor. Never on the delta loop of star delta configurations. There is no cost saving in so doing AND the relays perform with less likelihood of nuisance trips during the transition.
What is a thermal curve class?
All motor manufacturers can supply information on the insulating materials used in the construction of their motors (winding insulation), which is usually class F material insulation. In addition, they provide a means of determining the motor’s ability to dissipate heat. They provide this information by defining the safe cold stall time (at 40º) and safe hot stall time (at 120º) in seconds of the motor. In turn, these are referred by the protection industry as the cold thermal curve and the hot thermal curve respectively. Generally speaking there is a ratio of 3:1 between the cold and hot thermal curves.
Will a motor draw the same amount of current while starting Direct On Line as it would in a stall condition?
Yes. This will roughly equate to 6 times motor full load current and introduces important design criteria for the protection relay. Consider the following:
How will the protection relay actually determine that the motor is running when we start the motor? After all it could manifest a locked rotor on start up?
How will the protection relay identify a running stall situation or JAM condition?
How will the protection relay distinguish a short circuit condition from a running stall condition?
Will the thermal memory be retained if the power supply to the relay is removed?
Yes. The thermal condition of the protected motor is stored in a non-volatile memory area of the relay.
What are pre-loaded curves? Alternatively what is the meaning of pre-loading the protection relay?
When installing a brand new relay it is not possible for the protection relay to know the thermal condition of the protected motor at the point and time of installation since it is being newly installed. For that reason some protection relays will start with pre-loaded thermal curves. Typically this means that if you have selected a cold thermal curve of say 30 seconds, on power up, the protection relay will only make available 10 seconds. If a start is not initiated the protection relay will see no current flowing to the motor and will slowly allocate more thermal capacity until the full 30 second curve is once again available.
What is meant by failsafe?
It means that in the event of the power supply to the protection relay being removed, the main trip contact will de-energise and cause the main contactor holding coil to disengage and thus stop the motor.
Why Wait to Automate™ - Revolutionise Your Systems Today
Transform your existing systems with NewElec’s Why Wait to Automate™ initiative. Designed for diverse industries, our innovative solutions enable seamless integration of advanced automation without the need for expensive overhauls. Featuring minimal wiring changes, enhanced safety, and remote monitoring through SCADA or HMI/PLC systems, we deliver smarter control and optimized performance.
Our team works alongside you to simplify the transition, ensuring your operations become more efficient, connected, and future-ready. Take the step to automate today and redefine what’s possible with NewElec.
Why Choose NewElec for Your Pump Protection and Control Relays
Choose NewElec for state-of-the-art solutions tailored to your needs in the waterworks, water affairs, and water treatment industry. Our advanced pump motor protections, Dewatering Pump Relays, and integration-ready solutions enhance your operations and provide insights into motor health and performance. With a 20 to 30-year lifespan, our products are designed to last.
Why Choose NewElec for Your Protection and Control Relays
Choose NewElec for state-of-the-art Switchgear solutions tailored to your needs, backed by technical and functional expertise. Our range of motor protection relays, Earth Leakage Protection Relays, and Integration ready solutions enhance your operations and offer insight on motor health and performance. We offer feature-rich products with a 20 to 30-year lifespan.
Innovation drives us at NewElec. We develop products that push boundaries and meet future needs. Our commitment to innovation, quality, and customer support ensures reliable solutions when you need them.
Why Choose NewElec for Your Manufacturing Needs?
At NewElec, we deliver state-of-the-art motor control and protection solutions specifically designed for the manufacturing industry. Our feature-rich Motor Protection Relays and Earth Leakage Protection Relays enhance operational efficiency and provide valuable insights into motor health. Designed to last up to 30 years, our solutions help reduce long-term costs and deliver enduring value.
Innovation drives us—we continuously push the boundaries of technology to meet the evolving needs of manufacturers. Our commitment to quality and customer support ensures you always have reliable, high-performance solutions when you need them most.
Frequently Asked Questions:
Products
About Electronic Motor Protection Relays
Indeed. There are many satisfied users of thermal bi-metallic relays out there. They certainly hold a place in the market. However, our contention is that those users who are satisfied with this protection form have not had motors exposed to arduous working conditions. Almost certainly they have had the pleasure of uninterrupted balanced 3 phase supplies and you will find their motors frequently running well below full load current.
When considering that a 1% sustained overload is responsible for a 2 degree Centigrade temperature rise in the motor, that factors such as unbalanced phase currents and fluctuations in the supply voltage add to the creation of undesirable heat it becomes understandable that one would seek better and more accurate protection. Thermal bi-metals are mass produced items exhibiting a degree of inaccuracy when purchased off the shelve. They become less accurate with time (being electromechanical devices) and should be changed every 3 years to retain some degree of accuracy. They permit and tolerate immediate or near immediate re-sets, which suggests that, their thermal characteristics are not linked to the actual motor heat-cooling rate. Moreover these inexpensive devices are slow to respond to phase loss while the motor is running leading to rapid insulation winding degradation.
There are other reasons for which we would be opposed to using these devices BUT the above outlines the main reasons.
We are quick to point out that there are inexpensive electronic motor protection relays on the market that provide similar protection to the thermal bi-metal type. Acquiring these do not address the main points which are:
Accurate reliable overloading protection against both cyclic and sustained overloads with built-in thermal memory and capable of modelling two cooling rates. One for cyclic overloading and the other for when the motor is standing and no longer benefiting from the cooling fan .
Accurate and reliable phase unbalance and loss protection irrespective of motor loading with rapid tripping on phase loss.
Clear, latched fault diagnostic LEDs to assist maintenance personnel in establishing the nature of the fault.
NewElec motor protection products meet these BASIC and most important considerations throughout the entire range at all times.
If all of your relays provide the BASIC protection requirements that you have outlined above, what is the purpose of having the diverse range shown in your catalogue?
The short answer is that there are horses for courses?. This is where the more experienced electrical / instrumentation engineer needs to take a closer look at the application he/she is dealing with. Let us take time to ponder the issues involved. The answers to the following questions will ultimately determine the model preference.
- What motor starting method will be used?
- Is the protection relay going to be mounted on a door OR on a chassis plate inside the MCC cubicle?
- What physical space is available?
- Would integrated current transformers be a pre-requisite?
- Would it be better for the relay to be calibrated in amp or percentage?
- How long will the acceleration process likely take?
- What application is being considered?
- Would there be a need to protect against earth leakage faults?
- Does the present circuit incorporate a back up circuit breaker and is there a shunt tripping facility available?
- Will we require a 4-20mA output loop for use as an analogue input into a PLC for monitoring motor load?
- Would we want a duplicate set of trip contacts to signal to a remote control room?
- Would we wish to incorporate short circuit protection?
- Would it be required to allow for field bus communications to a PLC?
- Would you prefer to match more exactly the thermal characteristics of the motor to the protection relay?
- Is the detection of load loss required?
- Is the protection relay required to do recordings of the motor loads while running?
- Will jam protection be necessary?
- Will thermistor inputs be needed?
Will digital inputs for control purposes be required? Will the plant be fully automated by means of one or more PLCs?
These are some of the decision-making questions needing answers to make the wisest choice.
Questions Associated with the Newelec 320 - 327 Series
This problem is associated with the current transformers used during the installation which (if the relay is providing protection against earth fault and short circuit) should be class 5 P10. The problem can also manifest itself as a result of poor power factor correction and / or the use of a lot of VSDs. It all boils down to CT core saturation and harmonic content in the waveforms causing instability / spikes which is likely to occur when starting larger kW motors on DOL. You will need to do the following:
Ascertain there really is no earth fault present.
Start your motor while holding in the side mounted reset button.
On completion of the start sequence release the reset button.
If the protection relay trips on earth fault you will have to find the fault and clear it.
If no trip occurs, take a pair of side cutters and cut the solid wire link situated above the 47 Ohm stabilising resistor on the side of the relay. The problem will then be solved.
Questions Related to the Newelec N Series
This could be for any of the following individual or combination of reasons:
- The most frequent reason is that the 6 X I fl curve seconds is set differently on the respective relays
- The maximum load setting has not been set at the same level
- The motor r.m.s loading differs over a period of time
- One or more motors could have been stop/started consecutively prior to the observation
- One or more motors could be experiencing adverse unbalanced loading (low enough not to trip the motor on unbalance i.e less than 30%) but sufficiently so to reflect higher loading in the other phases and display a higher thermal usage content.
What is the purpose of the dial marked OVERLOAD CURVE 6 X I fl SECONDS mean? Is it the time required to accelerate my motor?
You are expected to set the safe cold stall time of the protected motor that is provided by the motor manufacturer. This could coincide with the acceleration time of the motor but need not necessarily be so. In essence the curve selection defines the acceptable thermal limits of the motor based on 6 times motor full load current. The setting should never be set above the safe cold stall time for the protected motor.
Why can’t I reset the overload protection relay after an overload trip?
Resetting the relay after an overload trip will not be tolerated until the thermal lockout LED extinguishes. The delay is forced to ensure the motor has sufficient time to cool off. Our design will allow the relay to be reset just as soon as the motor looses approximately 33% of its heat build up OR just as soon as the LED bar graph illumination reduces to the reset indicator.
What does the LED bar graph do?
It provides a visual indication of how hard the motor is working. The green LEDs act very much like a delayed ammeter, reflecting the motor loading at the time of observation. When the orange and red LEDs begin to illuminate they indicate that the motor is working very hard, often being overloaded, BUT still within the thermal handling capability of the insulation material. When the entire LED bar graph is lit, a thermal trip has occurred OR is about to occur.
Alternatively
This problem is associated with the current transformers used during the installation which (if the relay is providing protection against earth fault and short circuit) should be class 5 P10. The problem can also manifest itself as a result of poor power factor correction and / or the use of a lot of VSDs. It all boils down to CT core saturation and harmonic content in the waveforms causing instability / spikes which is likely to occur when starting larger kW motors on DOL. You will need to do the following:
Ascertain there really is no earth fault present.
Start your motor while holding in the side mounted reset button.
On completion of the start sequence release the reset button.
If the protection relay trips on earth fault you will have to find the fault and clear it.
If no trip occurs, take a pair of side cutters and cut the solid wire link situated above the 47 Ohm stabilising resistor on the side of the relay. The problem will then be solved.
The start timer setting on your 327 M relay only permits us a maximum setting of 21 seconds. Our application requires 32 seconds. Consequently we are unable to start our motor without tripping. How can we overcome this difficulty?
It is possible to alter the start timer seconds range by applying a multiplying factor of 4 to the scale. If this is done the timing scale will extend to 4 to 84 seconds from an initial 1 to 21 seconds. This can be achieved by opening the relay (4 rear base mounted screws must be removed) and sliding the relay slowly out of its casing. YOU NEED NOT SLIDE THE ENTIRE RELAY OUT OF ITS HOUSING! TWO THIRDS OF THE WAY IS SUFFICIENT. When you are able to see two bank sets of 8 dip switches exposed to your view, select dip switch bank PSS2 and move dip switch 1 to the off position.
Would it be possible to change the auxiliary supply operating voltage of your 320 to 327 relays without returning the unit(s) to your factory for alteration?
Yes. This is made possible by shifting a slide switch inside the relay from one position to the other. This can be achieved by opening the relay (4 rear base mounted screws must be removed) and sliding the relay slowly out of its casing. YOU NEED NOT SLIDE THE ENTIRE RELAY OUT OF ITS HOUSING! TWO THIRDS OF THE WAY IS SUFFICIENT. Look for a black slide switch on the top PC Board. The PC Board is marked 320 AD and is the board that includes the power transformers. Once you have found the slide switch move it from the 110 V to 220 V position or vice-versa.
How NewElec’s KD Relay Protects Crusher Motors and Enhances Efficiency
Adjustable Settings for Customisation
A standout feature of thermal overload relays is their adjustability. Most relays allow engineers to set the current trip threshold according to the motor’s specifications. This customisation ensures that the relay responds precisely to the motor’s needs, avoiding unnecessary shutdowns while maintaining robust protection.
Ease of Use and Maintenance
Thermal overload relays are known for their user-friendly design. Their straightforward operation minimises the learning curve for technicians and maintenance personnel. Additionally, their simplicity translates to easier maintenance and troubleshooting, making them a practical choice for busy industrial environments.
Automatic Reset Capabilities
Certain thermal overload relays offer an automatic reset feature, enabling the motor to restart once normal conditions are restored. This functionality is particularly useful in applications where continuous operation is critical, as it reduces downtime and manual intervention.
Enhancing Equipment Lifespan
Thermal Overload Relays protect motors and other electrical devices from wear and tear caused by electrical overcurrents. Without adequate protection, excessive heat can degrade insulation, warp mechanical components, and lead to recurring breakdowns. By ensuring that equipment operates within its specified parameters, these relays help extend the lifespan of motors, reducing replacement costs and supporting a longer return on investment for industrial assets.
How NewElec’s KD Relay Protects Crusher Motors and Enhances Efficiency
Motor relay management systems offer advanced monitoring and protection for industrial motors. These systems provide real-time data on motor performance, fault conditions, and energy usage, allowing for informed decision-making. For example, the NewElec KG/KH 3 Phase Motor Relay revolutionises motor protection with features like power quality monitoring, feeder protection, and Bluetooth LE connectivity. The ability to configure and analyse motor data remotely makes this relay an ideal solution for industries integrating into Industry 4.0 environments.
In a large industrial facility, remote monitoring with systems like the KG/KH Relay ensures that critical motor parameters are accessible to decision-makers from anywhere. This capability allows for continuous system optimisation, real-time diagnostics, and predictive maintenance, reducing the risk of failure and extending equipment lifespan. Using the KG/KH Relay, a business can analyse motor performance data, predict potential faults, and schedule maintenance well before a motor fails. This proactive approach not only prevents costly repairs but also enhances the reliability and efficiency of industrial processes.
What is a GA-Plus Relay?
The GA-Plus Relay is a specific type of protective relay from NewElec with advanced capabilities for detecting and responding to earth leakage and other electrical faults. It is designed for use in harsh industrial environments.
Frequently Asked Questions:
Industry Solutions
About Problems Experienced on Site
Check for reverse installed current transformers. Also check for faulty current transformer as well as insuring that all current transformers used have the same secondary output current. Should all the aspects mentioned be satisfactory, check for loose connections, and effectiveness of any 3 phase closing isolating switches, contactors and circuit breakers and back-up fuses on the main phase lines to the motor. Taking readings of actual individual phase currents while the motor is running in order to establish the actual current variance between phases may also be necessary as a check. On those models permitting the user to set the unbalance trip thresholds you may find the setting somewhat tight. Consider any other applications in your plant that could have an impact on your power distribution network (for example the operation of an arc furnace).
I am using one of your relays having a fixed 15-second cold thermal curve on a conveyor belt motor requiring 27 seconds to reach full operating speed. It is a D.O.L application involving a 110 kW motor at 380 Volt a.c. Your relay keeps tripping on overload?
The cold / hot thermal motor protection curves are always based on 6 times motor full load setting. Since, in the case mentioned above, your motor will be drawing this inrush current for considerably more than the permissible 15 seconds (cold start class) it is expected (and quite normal) that the motor protection relay will behave in the manner you have described. The solution to the problem is in the selection of the correct protection relay, which should allow for a larger motor thermal capacity. Select a motor protection relay that supports user selectable cold / hot thermal curves OR one that ignores the inrush current for a user selected time period. The latter may solve the practical onsite problems but is not a solution in the longer term since it exposes your motor to the possibility of a locked rotor condition during starting. In this case consider using another device such as a tachometer to insure the motor is actually turning and picking up speed. In some cases the motor selected for the application may need to be revised.
Our geographic location is highly prone to lightning strikes. Are your NewElec relays protected against such high voltage surges on the network?
Yes, the relays are adequately protected. But in addition, the motor itself must be protected at the motor terminals with a surge arrester connected to a good earth connection to limit voltage surges on the motor windings.
What Is Vibration Monitoring?
Vibration monitoring is a maintenance strategy that involves measuring and analysing the vibrations of rotating equipment to assess its operational health. This technique uses sensors such as accelerometers, proximity probes, and velocity transmitters to gather data on vibration levels. By comparing this data to predefined thresholds or historical baselines, operators can identify anomalies indicative of mechanical problems.
For example, a pump exhibiting unusual vibration patterns may have issues such as misalignment, imbalance, or bearing wear. Addressing these problems early not only prevents costly breakdowns but also extends the lifespan of the equipment and reduces operational costs.
Benefits of Vibration Monitoring
1. Enhanced Equipment Efficiency:
Regular vibration analysis ensures that machinery operates at optimal performance levels. Identifying and correcting inefficiencies, such as loose components or misaligned shafts, minimises energy waste.
2. Reduced Downtime:
Unplanned downtime is a significant challenge in water treatment plants. Continuous vibration monitoring enables early fault detection, allowing for timely repairs that prevent extended outages.
3. Prolonged Equipment Lifespan:
By addressing mechanical issues promptly, vibration monitoring helps extend the service life of critical machinery. This reduces replacement costs and aligns with sustainability goals.
4. Improved Safety and Compliance:
Excessive vibrations can lead to catastrophic equipment failure, posing risks to personnel and the environment. Monitoring systems help mitigate these risks, ensuring compliance with safety regulations and operational standards.
Why Vibrations Occur in Industrial Equipment
Several factors contribute to vibrations in industrial machinery, including:
- Misalignment: Improper alignment of shafts or components creates uneven forces, leading to excessive vibrations.
- Imbalance: An uneven distribution of mass in rotating parts, such as pump impellers, results in centrifugal forces that cause vibration.
- Looseness: Components that are not securely fastened can create additional movement, amplifying vibrations.
- Bearing Wear: Over time, bearings experience wear due to contamination, insufficient lubrication, or mechanical stress, leading to increased vibration levels.
Understanding these root causes is essential for diagnosing and addressing equipment issues effectively.
Benefits and Applications of Integrating Vibration Monitoring with Protection Relays
By integrating vibration monitoring in protection relays soon, water treatment plants can safeguard critical processes and prevent costly disruptions. For example, in lift pumps, vibration sensors detect early signs of bearing stress or misalignment, while KE Series Relays and KD Series Relays initiate safe shutdowns to avoid catastrophic failures. Similarly, in filtration systems, relays ensure backflush pumps operate within safe parameters during demanding cycles, reducing downtime and extending equipment lifespan. These practical applications demonstrate how vibration monitoring and protection relays work together to maintain seamless operations.
This synergy is particularly impactful in key processes like lift pumps and filtration systems, where uninterrupted functionality is crucial. For example:
- Lift Pumps: Vibration sensors detect mechanical stress or wear in bearings, while relays initiate safe shutdowns or alerts to prevent further damage.
- Filtration Systems: Relays monitor and protect backflush pumps, ensuring they operate within safe parameters during demanding cycles.
By combining these technologies, water treatment plants can minimise downtime, optimise equipment performance, and achieve sustainable operations.
How Overload Thermal Relays Work
Thermal overload relays are built around a straightforward principle: monitoring heat generated by current flow. At the core of many relays is a bimetallic strip, a component that bends or flexes when exposed to heat. As the motor operates, current flows through the relay, generating heat proportional to the electrical load. If the current exceeds a predetermined threshold, the bimetallic strip bends to a point that triggers the relay, cutting off power to the motor. This automatic response ensures that motors do not run beyond safe limits. The mechanism also accounts for temporary surges, as relays are calibrated to differentiate between brief spikes and sustained overload conditions.Electronic overload relays, in contrast, utilise advanced sensors to monitor current fluctuations with greater precision. These devices can diagnose faults, log operational data, and provide real-time alerts, making them ideal for industries requiring highly accurate and customisable motor protection.
What is a Motor Control System?
A motor control system refers to a set of devices or circuits used to start, regulate, and stop an electric motor. These systems ensure motors run smoothly, efficiently, and within safe operational parameters. Motor control systems are crucial in managing the energy use, safety, and performance of motors, which are often the workhorses of industrial applications, driving pumps, conveyors, fans, compressors, and more.
The fundamental role of motor control is to manage the operational behavior of the motor, such as starting and stopping, adjusting speed, and ensuring the motor operates without overload or overheating. Depending on the industrial process, different control methods can be applied:
- Manual Motor Control: In smaller or less automated environments, manual motor control is used. Operators manually start and stop the motors, but this method can introduce inefficiencies such as human error or delayed response times.
- Automatic Motor Control: In automated systems, motors are controlled by programmed systems that monitor operational conditions and optimise motor performance automatically, reducing the need for human intervention.
- Remote Motor Control: Remote control allows operators to manage motor systems from a distance using technologies like wireless connectivity. This is especially useful in large facilities where physical proximity to equipment is not always practical.
Frequently Asked Questions:
Thermal Overload Relays
How do I choose between a thermal overload relay and a multi-function relay?
Thermal overload relays are ideal for straightforward motor protection. Multi-function relays, with features like fault diagnostics and phase failure monitoring, are better suited for complex operations requiring additional safeguards.
What maintenance is required for thermal overload relays in high-demand industries?
Regularly inspect relays for wear, calibrate trip settings, and clean components to ensure optimal performance in high-demand environments like mining or manufacturing.
What factors should be considered when selecting an overload relay?
When choosing an overload relay, key factors to consider include:
- Motor Type and Size: Ensure the relay matches the motor’s rated current and phase configuration.
- Operating Environment: For environments with high vibration, dust, or extreme temperatures, consider electronic relays with enhanced durability.
- Application Requirements: Evaluate the need for additional features such as fault diagnostics, data logging, or automatic reset capabilities.
- Industry Standards: Ensure compliance with safety and industry-specific standards (e.g., IEC or NEMA ratings).
How do thermal overload relays differ from circuit breakers?
While both devices protect electrical systems, their roles and mechanisms differ:
- Thermal Overload Relays: Focus on protecting motors from prolonged overheating due to excessive current.
- Circuit Breakers: Protect entire circuits from short circuits and instantaneous overcurrent conditions. Using them together offers comprehensive motor and system protection.
Can thermal overload relays be used with variable frequency drives (VSDs)?
Yes, but special considerations are required. Some relays may not accurately sense current variations caused by VSDs. In such cases, electronic relays designed to work with VSDs are recommended for reliable protection. The Newlec LA Series Relays are often fitted below Variable Speed Drives (VSD).
What is the lifespan of a thermal overload relay?
The lifespan depends on:
- Operating Conditions: Extreme heat, vibration, or frequent overload events can reduce longevity.
- Maintenance: Regular inspections, cleaning, and recalibration extend the life of the relay. On average, a well-maintained relay can last several years under normal conditions.
Newelec has a design philosophy keeping long-term protection in mind, our relays are designed to last 25-30 years and allow for field upgrades.
How can I test the functionality of a thermal overload relay?
To test a thermal overload relay:
- Simulate an overload condition by increasing the motor load or using a test device or Newelec Front-End Software Simulator.
- Observe if the relay trips at the specified current.
- Check for proper reset functionality after the trip. Always follow the manufacturer’s testing procedures to ensure accurate results.
- Record Fault and Event records over a pre-determined period with NewElec’s Front-end recorder and export to excel for analysis.
What are common signs of a faulty overload relay?
Indicators of a faulty relay include:
- Motors failing to start or frequently tripping without apparent overloads.
- Delayed or no response to actual overload conditions.
- Burnt or discolored components indicating overheating or electrical damage.
Frequently Asked Questions:
Key Terminology in Earth Leakage Protection
What is an Earth Leakage Relay?
An Earth Leakage Relay is a device that detects earth leakage currents (small stray currents that escape from an electrical circuit) and trips the circuit to prevent electrical hazards.
What does Earth Leakage Protection do?
Earth Leakage Protection is a safety measure designed to detect and interrupt leakage currents to prevent electrical shocks, fires, and equipment damage. It is essential for enhancing safety in mining operations.
What are Protective Relays?
Protective Relays are electrical devices designed to trip a circuit breaker when a fault is detected. They are crucial for protecting electrical systems from damage caused by overloads, short circuits, or other electrical faults.
Why is Fan Motor Protection important?
Fan Motor Protection ensures that fan motors do not overheat, suffer from electrical faults, or run inefficiently. This helps maintain operational safety and efficiency.
What is an Overload Protection Relay?
An Overload Protection Relay protects electrical equipment from excessive current, which can cause overheating and damage. It trips the circuit when an overload condition is detected.
What is Slurry Pump Protection?
Slurry Pump Protection involves protective measures specifically for slurry pumps, which handle abrasive and corrosive materials. This ensures the pumps operate safely and efficiently, reducing downtime and maintenance costs.
What does Pump Motor Protection involve?
Pump Motor Protection includes safety measures and devices designed to protect pump motors from electrical faults, overloads, and other operational issues, ensuring reliable performance in industrial applications.
What is a CT (Current Transformer) with Additional Test Windings?
A CT with Additional Test Windings is a type of current transformer that includes extra windings specifically for testing purposes. These additional windings enhance the ability to measure and monitor earth leakage currents accurately.
What is Earth Fault Protection?
Earth Fault Protection is a safety mechanism that detects and protects against earth faults (unintentional electrical paths to the ground), which can cause equipment damage and pose safety hazards.
What does an Earth Fault Relay do?
An Earth Fault Relay is designed to detect earth faults and trip the circuit to prevent electrical hazards.
What is Earth Leakage Core Balance?
Earth Leakage Core Balance is a method used to detect earth leakage by measuring the imbalance in the current flowing through the conductors. It ensures sensitive and accurate detection of leakage currents.
What is Earth Insulation Lockout?
Earth Insulation Lockout is a safety feature that prevents the operation of electrical equipment if there is a fault in the insulation, thereby preventing electrical hazards.
What does Earth Insulation Protection entail?
Earth Insulation Protection includes measures that ensure the integrity of the electrical insulation, preventing leaks and ensuring the safe operation of electrical equipment.
