Dynamic Load Testing Matters!02/24/2017You’ve probably heard the phrase before, but do you really know what “Dynamic Load Testing” means or why it is important? Let’s take this matter one step at a time to better understand the subject, and how it relates to testing AC drives and DC drives. Load Testing is the process of subjecting something to a work level that is near or at its rated capacity or limit. This can be done to software, a bridge, a car’s motor, or an electronic device, which in our case is AC & DC motor controls (or drives). An easy to understand example of an electronic device is the electronic power supply. If the unit’s function is to turn AC line voltage into a steady DC output voltage, it will have a maximum current rating for that output voltage. A common failure of a power supply is that it puts out the proper voltage with nothing connected to its output, but when it is connected to what it supplies power to, the output voltage is reduced or goes away completely. A way to check to see that the power supply functions properly is to apply a load to the power supply’s output that draws a current that is near the maximum output current rating. If the power supply’s output rating is 5VDC @ 5A of current, ohms law can be used to calculate the proper load required to draw the maximum current. We will use a resistor as a load, and since ohm’s law states R = E/I (resistance = voltage divided by current), that calculates to R = 5/5, which is 1 ohm of resistance to draw 5A of current. Connecting a 1 ohm resistor to the power supply’s output will prove the supply can put out its rated current, and thus we have Load Tested the unit. *A consideration in this example is the power rating of the load resistor, but we’ll leave that discussion for another time. There are several types of load testing, and being that this article is related to motor controls, we’ll look at Static Load Testing and Dynamic Load Testing.Static Load Testing is applying a constant fixed load to something to test its ratings, which is what was applied to the power supply example. The output load did not vary, it was fixed and a fixed output current was the result. Static load testing is good, but can miss problems that might show up with a varying load applied to the item under test. Dynamic Load Testing is the application of a varying load to test an items capacity. An easy way to understand the difference is to consider a floor of a structure. A static load test would be to have a number of people stand on the floor, and a dynamic load test would be to have fewer people jumping up and down on the floor – you get the idea. Now let’s get to the main point – when it comes to testing a motor control, Why Does Dynamic Load Testing Matter? Motors are the work horse of industry, and in today’s manufacturing the majority of these motors are controlled by AC drives and DC drives. The power rating of these motors and drives vary greatly, from a fraction of a horsepower to thousands of horsepower, in extremely large applications. To properly test these motor controls, they must be load tested to prove they can supply the proper output (current and voltage) to the motor per their nameplate ratings. This is done by the control’s manufacturer as a quality control during manufacturing, and it should be done when any parts within the unit are replaced to ensure it can perform to its rated specifications. If not, it’s just like the power supply – it will look fine with no load, but when put to the test it may fail horribly. This is NOT something you want to happen at your facility when you re-install a repaired AC drive or DC drive! When a motor control is load tested, the test should simulate the varying load that it can be subjected to in the real world application in which it is used. It is true that in some applications, the load does not vary and stays fairly constant, but this is rarely the case – think of a pump, crane hoist, stamping press and other cyclical loads. Here at PES, all repaired AC Drives, DC drives and other motor controls are tested under dynamic load on our custom engineered load centers. This equipment uses motors that are coupled to a dynamic load to prove the repaired control will hold up when put back into its application, no matter what the application is, because after all . . . Dynamic Load Testing Matters!! Call us today at 800-732-4695 to find out more. Back To Blog
Dynamic Load Testing Matters!02/24/2017You’ve probably heard the phrase before, but do you really know what “Dynamic Load Testing” means or why it is important? Let’s take this matter one step at a time to better understand the subject, and how it relates to testing AC drives and DC drives. Load Testing is the process of subjecting something to a work level that is near or at its rated capacity or limit. This can be done to software, a bridge, a car’s motor, or an electronic device, which in our case is AC & DC motor controls (or drives). An easy to understand example of an electronic device is the electronic power supply. If the unit’s function is to turn AC line voltage into a steady DC output voltage, it will have a maximum current rating for that output voltage. A common failure of a power supply is that it puts out the proper voltage with nothing connected to its output, but when it is connected to what it supplies power to, the output voltage is reduced or goes away completely. A way to check to see that the power supply functions properly is to apply a load to the power supply’s output that draws a current that is near the maximum output current rating. If the power supply’s output rating is 5VDC @ 5A of current, ohms law can be used to calculate the proper load required to draw the maximum current. We will use a resistor as a load, and since ohm’s law states R = E/I (resistance = voltage divided by current), that calculates to R = 5/5, which is 1 ohm of resistance to draw 5A of current. Connecting a 1 ohm resistor to the power supply’s output will prove the supply can put out its rated current, and thus we have Load Tested the unit. *A consideration in this example is the power rating of the load resistor, but we’ll leave that discussion for another time. There are several types of load testing, and being that this article is related to motor controls, we’ll look at Static Load Testing and Dynamic Load Testing.Static Load Testing is applying a constant fixed load to something to test its ratings, which is what was applied to the power supply example. The output load did not vary, it was fixed and a fixed output current was the result. Static load testing is good, but can miss problems that might show up with a varying load applied to the item under test. Dynamic Load Testing is the application of a varying load to test an items capacity. An easy way to understand the difference is to consider a floor of a structure. A static load test would be to have a number of people stand on the floor, and a dynamic load test would be to have fewer people jumping up and down on the floor – you get the idea. Now let’s get to the main point – when it comes to testing a motor control, Why Does Dynamic Load Testing Matter? Motors are the work horse of industry, and in today’s manufacturing the majority of these motors are controlled by AC drives and DC drives. The power rating of these motors and drives vary greatly, from a fraction of a horsepower to thousands of horsepower, in extremely large applications. To properly test these motor controls, they must be load tested to prove they can supply the proper output (current and voltage) to the motor per their nameplate ratings. This is done by the control’s manufacturer as a quality control during manufacturing, and it should be done when any parts within the unit are replaced to ensure it can perform to its rated specifications. If not, it’s just like the power supply – it will look fine with no load, but when put to the test it may fail horribly. This is NOT something you want to happen at your facility when you re-install a repaired AC drive or DC drive! When a motor control is load tested, the test should simulate the varying load that it can be subjected to in the real world application in which it is used. It is true that in some applications, the load does not vary and stays fairly constant, but this is rarely the case – think of a pump, crane hoist, stamping press and other cyclical loads. Here at PES, all repaired AC Drives, DC drives and other motor controls are tested under dynamic load on our custom engineered load centers. This equipment uses motors that are coupled to a dynamic load to prove the repaired control will hold up when put back into its application, no matter what the application is, because after all . . . Dynamic Load Testing Matters!! Call us today at 800-732-4695 to find out more.