Basics | Design World Motion Handbook

What is nested vector interrupt control (NVIC)?

March 20, 2019 By Danielle Collins Leave a Comment

In a microcontroller, such as those at the heart of industrial motion controllers, interrupts serve as a way to immediately divert the central processing unit from its current task to another, more important task.

An interrupt can be triggered internally from the microcontroller (MCU) or externally, by a peripheral. The interrupt alerts the central processing unit (CPU) to an occurrence such as a time-based event (a specified amount of time has elapsed or a specific time is reached, for example), a change of state, or the start or end of a process.

Interrupts can be triggered internally – from a timer, for example – or externally, from peripherals.

Another method of monitoring a timed event or change of state is referred to as “polling.” With polling, the status of a timer or state change is periodically checked. The downsides of polling are the risk of excessive latency (delay) between the actual change and its detection, the possibility of missing a change altogether, and the increased processing time and power it requires.

With polling, the CPU periodically checks for a change of state. Interrupts automatically notify the CPU when a change of state occurs, ensuring the change is not missed and its detection is not delayed.
Image credit: Renesas Electronics Corporation

When an interrupt occurs, an interrupt signal is generated, which causes the CPU to stop its current operation, save its current state, and begin the processing program — referred to as an interrupt service routine (ISR) or interrupt handler — associated with the interrupt. When the interrupt processing is complete, the CPU restores its previous state and resumes where it left off.

Nested vector interrupt control (NVIC) is a method of prioritizing interrupts, improving the MCU’s performance and reducing interrupt latency. NVIC also provides implementation schemes for handling interrupts that occur when other interrupts are being executed or when the CPU is in the process of restoring its previous state and resuming its suspended process.

The term “nested” refers to the fact that in NVIC, a number of interrupts (up to several hundred in some processors) can be defined, and each interrupt is assigned a priority, with “0” being the highest priority. In addition, the most critical interrupt can be made non-maskable, meaning it cannot be disabled (masked).

One function of NVIC is to ensure that higher priority interrupts are completed before lower-priority interrupts, even if the lower-priority interrupt is triggered first. For example, if a lower-priority interrupt is being registered* or executed and a higher-priority interrupt occurs, the CPU will stop the lower-priority interrupt and process the higher-priority one first.

* A register is a special, dedicated memory circuit within the CPU that can be written and read much more quickly than regular memory. The register is used to store information such as calculation results, CPU execution states, or other critical program information.

Similarly, a handling scheme referred to as “tail-chaining” specifies that if an interrupt is pending while the ISR for another, higher-priority another interrupt completes, the processor will immediately begin the ISR for the next interrupt, without restoring its previous state.

With tail-chaining, if an interrupt is pending as the ISR for another, higher-priority interrupt completes, the processor will immediately begin the ISR for the next interrupt, without restoring its previous state.
Image credit: Arm Limited

The term “vector” in nested vector interrupt control refers to the way in which the CPU finds the program, or ISR, to be executed when an interrupt occurs. Nested vector interrupt control uses a vector table that contains the addresses of the ISRs for each interrupt. When an interrupt is triggered, the processor gets the address from the vector table.

The prioritization and handling schemes of nested vector interrupt control reduce the latency and overhead that interrupts typically introduce and ensure low power consumption, even with high interrupt loading on the controller.

Feature image credit: Arm Limited

What is Space Vector Pulse Width Modulation (SVPWM)?

March 14, 2019 By Danielle Collins Leave a Comment

One common, modern method for controlling three-phase induction motors and permanent magnet synchronous motors (aka BLAC or PMAC motors) is field oriented control, which independently controls the magnetizing and torque-producing components of the stator current. This allows the torque-producing component to be kept orthogonal to the rotor flux, maximizing torque production.

Space vector pulse width modulation (SVPWM) is a technique used in the final step of field oriented control (FOC) to determine the pulse-width modulated signals for the inverter switches in order to generate the desired 3-phase voltages to the motor.

Field oriented control with space vector pulse width modulation.
Image credit: Texas Instruments

The following is a summary of how FOC with SVPWM operates:

1) Measure two of the three motor phase currents and feed them into a Clarke transform to convert them from a three-phase system (i_a, i_b, i_c) to a two-dimensional orthogonal system (i_α, i_β). Note that it’s not necessary to measure all three currents, since the sum of the three must equal unity (0). So the third current must be the negative sum of the first two.

2) Apply a Park transform to convert the two-axis stationary system (i_α, i_β) to a two-axis rotating system (i_q, i_d), where the d axis current is aligned to the rotor flux and the d axis current (the torque-producing component) is orthogonal to the rotor flux.

3) The stator current flux and torque are controlled independently, typically by PI controllers. Voltages to be applied to the motor, V_dand V_q, are determined from the PI controllers.

4) Next, an inverse Park transform converts the two-axis rotating system (V_sqref, V_sdref) back to a two-axis stationary system (V_s_αref, V_s_βref). These are the components of the stator voltage vector and are the inputs for the SVPWM, which generates the 3-phase output voltage to the motor. (Note that the use of SVPWM eliminates the need for an inverse Clarke transform to obtain the three-phase output voltages.)

Field oriented control transforms a three-phase system time-dependent system into a two-coordinate (d and q), time-invariant system. SVPWM is used in the final step to determine the PWM signals to be applied to the motor.
Image credit: Freescale Semiconductor

The details behind SVPWM

Voltage is delivered to the motor by a three-phase inverter with six transistors (two on each leg of the output). Each of the three outputs can be in one of two states (top transistor closed and bottom transistor open, or vice-versa), giving eight (2³) total states for the output. These are referred to as base vectors.

For each leg of the inverter output, either the top transistor will be open and the bottom closed, or vice-versa. Therefore, there are eight total states (2³) for the inverter output.
Image credit: switchcraft.org

The eight base vectors are plotted on a hexagonal star diagram. Each vector makes up a spoke of the star, with 60 degrees phase difference between adjacent vectors. The two vectors (V₀ and V₇) that contain outputs which are either all plus or all minus are referred to as null vectors and are plotted at the center (origin) of the star.

Each base vector makes up one segment of a hexagonal star, with the null vectors (V₀ and V₇) plotted in the center.

The goal of SVPWM is to produce a “mean vector” during the PWM period (T_PWM) that is equal to the desired voltage vector (V_out).

The location of V_out is determined on the star diagram, and the base vectors that constrain that sector (V₁ and V₃, for example), along with one of the null vectors, are used to synthesize the desired voltage. This is done by applying V₁for a specified time (T₁), V₃for a specified time (T₃), and the null vector for the amount of time necessary (T₀) to provide a resultant vector equal to V_out.

The values of T1, T3, and T₀ can be determined with the following equations:

The simulation of V_out can then be expressed as:

Compared to standard field oriented control, using FOC with space vector pulse width modulation enables more efficient use of the DC supply voltage, provides lower harmonic distortion — which improves power factor — and reduces torque ripple.

What are photoelectric proximity sensors?

March 12, 2019 By Miles Budimir Leave a Comment

Proximity sensors are used to sense the presence of objects or materials across a broad range of industrial and manufacturing applications. Key to their operation is that they don’t require physical contact with the target or object being sensed. This is why they’re often called non-contact sensors.

One of the most common types of proximity sensor is the photoelectric sensor. These sensors detect objects directly in front of them by the detecting the sensor’s own transmitted light reflected back from an object’s surface. A common arrangement is that both the emitter and receiver are housed in the same unit, but not all photoelectric sensors are constructed this way.

An example of a reflective sensor with both the emitter and receiver in a single housing. (Image via Pepperl+Fuchs)

There are three basic configurations for photoelectric proximity sensors; reflective, through-beam, and proximity.

Reflective sensors – In this type of sensor, a beam of light is sent out from an emitter and is bounced off of a reflector back to a detector. When the light beam is able to reflect back, this registers as no object being present. The beam failing to reflect back means there is an obstruction, which registers as the presence of an object. These sensors are less accurate than other types, but they’re also easier to install and wire and typically cost less than through-beam sensors.

The diagram shows a typical through-beam photoelectric sensor setup with separate emitter and receiver components. A break in the light beam indicates the presence of an object. (Image via Omron Industrial Automation)

Through-beam sensors – In this type of setup, an emitter sends out a beam of light usually directly in the line-of-sight of the emitter to a receiver. When an object breaks this beam of light, it’s detected as a presence. This type of setup requires two components; an emitter and a separate detector, which makes it a bit more complex to install and wire. However, the advantage is that it’s the most accurate of the sensing methods with the longest sensing range.

Proximity (diffuse) sensor – Diffuse photoelectric sensors are similar in some respects to reflective sensors. This is because like reflective sensors they emit a light beam in the direction of the object to be detected. However, instead of a reflector used to bounce the light back to a detector, the object to be sensed functions as the reflector, bouncing some of the light back to be detected and register an object’s presence.

What are pallet conveyors? (Not to be confused with pallet-moving conveyors)

March 8, 2019 By Danielle Collins Leave a Comment

Pallet conveyors transfer discreet products on carriers referred to as “pallets,” typically transported by belt, roller chain, flat-top chain, or for extremely high loads, powered rollers.

For the heaviest loads, in applications such as appliance assembly and automotive manufacturing, pallets are transported by rollers.
Image credit: Bosch Rexroth Corporation

Although they’re typically offered in standard sizes, pallets can be tooled with custom fixtures to locate and secure the product on the pallet.
Image credit: Glide-Line

Pallet sizes are, for the most part, standardized among manufacturers in metric dimensions (240 x 240 mm, for example), although some manufacturers offer pallets in inch or non-standard metric dimensions. In many cases, conveyor pallets are tooled with custom fixtures to locate and secure the product on the pallet. So not only can the pallet be accurately positioned on the conveyor, but the product can be precisely located on the pallet. This makes pallet-based conveyors the ideal solution for high-precision assembly, machining, inspection, and positioning tasks.

Note that the pallets discussed here are different from the pallets used for storing and handling bulk goods, which are often made of wood or plastic. Similarly, some roller- and chain-driven conveyors are marketed as “pallet conveyors,” for the transportation of these wooden or plastic pallets through a factory or warehouse.

Pallets can be transported around corners without changing the pallet orientation.
Image credit: Dorner Mfg. Corp.

Pallet conveyors are suitable for transporting products in two dimensions, but can accommodate small elevation changes. Curved sections — typically from 15 to 180 degrees — allow conveyors to change the direction of transport while maintaining pallet orientation. Conveyor modules referred to as “lift and rotate” units allow the orientation of the pallet to be changed while maintaining the direct of transport. Pallets can also be lifted and precisely located, for positioning at a workstation or inspection area, where pallet conveyors allow access to the workpiece from more than one side. For access to the bottom of the workpiece, pallets can be made with an open center.

The use of pallets to move individual products allows non-synchronous movement, so each product can be transported and routed independently. Because the pallets are precisely machined, they can be accurately positioned and located via sensors, and RFID tags or other data carriers can be attached to each pallet to track and document individual product movements. Pallets can be diverted and merged for offline operations, and accumulation allows products to be buffered, smoothing the flow of downstream operations.

Here, pneumatic cylinders are used to stop and lift the pallet. Precise locating is achieved by pins that mate to bushings on the pallet.
Image credit: mk North America, Inc.

Most pallet conveyors — especially those used in automation applications — are modular, based on standard conveyor sections, legs, and lift/transfer/rotate modules that can be easily reconfigured or expanded as needs change. And because components are standardized, pallet-based conveyors can be configured to meet a wide range of environmental requirements, including cleanroom, dry room, washdown, and ESD-compatible applications.

Feature image credit: Dorner Mfg. Corp.

Gearmotors and reflected mass inertia from the load: Part 2

March 1, 2019 By Miles Budimir Leave a Comment

In an earlier article on the impact of gearmotors on the reflected mass inertia from the load, we made some assumptions about the inertia of system components which weren’t explicit and which could lead to error in the calculation and cause problems in an actual application. This came to our attention via a sharp-eyed reader’s comment so to make things right, we’re clarifying a few points to more accurately reflect (sorry for the pun) the nature of inertia calculations.

Pictorial representation of a drive system with gears. (Image via Omron Industrial Automation)

Specifically, what we left out was the inertia of the gear train as well as any elements of the motor connection system itself. Leaving these inertia values out of the overall calculation produces an incorrect value for overall inertia and can lead to undersizing input torque requirements.

What’s missing from the total system inertia is the inertia of the gears themselves and any other components of the connection system such as couplings. Another factor to keep in mind is that even with the same ratio different types of speed reduction and couplings may have different inertia values.

The key point is this: If the gear reducer is added separately, then the inertia value of the gears (usually provided by the manufacturer) needs to be added into the total system inertia. However, when purchasing a complete gearmotor, check with the manufacturer to determine if the published gearmotor inertia value includes the inertia of the internal gear reducer.

The bottom line is when calculating the total inertia for any motion system, the final value must include the inertia of all rotating parts, including the drive (such as a belt and pulley system, screw, or rack and pinion, etc.), the load being moved, the motor, the gearbox (if used in the system) and the coupling between the load and the motor.

What is plugging for electric motors?

February 26, 2019 By Danielle Collins Leave a Comment

There are generally three types of electrical braking for motors: regenerative braking, dynamic braking, and plugging. Of the three methods, plugging provides the fastest stop, but it can be harsh on both the electrical and mechanical components. Because of this, it’s the least commonly used method of braking, but it is appropriate for some applications.

Plugging can be more harsh on electrical and mechanical components, but it provides a faster stop than dynamic braking methods.
Image credit: secs.oakland.edu

Plugging — sometimes referred to as “reverse current braking” — is possible on both DC motors and AC induction motors. For DC motors, plugging is achieved by reversing the polarity of the armature voltage. When this happens, the back EMF voltage no longer opposes the supply voltage. Instead, the back EMF and the supply voltage work in the same direction, opposing the motor’s rotation and causing it to come to a near-instant stop. The reverse current produced by the combined supply voltage and back EMF is extremely high, so resistance is placed in the circuit to limit the current.

DC motor circuits for regular motoring operation (left) and for plugging (right). Notice that for plugging operation, the armature voltage is reversed and resistance is added to the circuit.

For AC induction motors, the stator voltage is reversed by interchanging any two of the supply leads. The field then rotates in the opposite direction and the motor’s slip (the difference between the speed of the stator’s rotating magnetic field and the speed of the rotor) becomes greater than unity (s > 1). In other words, the rotor spins faster than the rotating magnetic field in the stator. Torque is developed in the opposite direction of the motor’s rotation, which produces a strong braking effect.

Slip, which is the difference between the speed of the stator’s rotating magnetic field and the speed of the rotor, is a fundamental property of AC induction motors. In normal motoring operation, the rotor spins at a slower rate than that of the stator’s rotating magnetic field.

When the motor speed reaches zero, if it is not disconnected from the supply, it will begin to reverse, or rotate in the opposite direction. In some applications, reversal of the motor’s direction is the goal. But when plugging is used to brake the motor, a zero-speed switch or plugging contactor is used to disconnect the motor from the supply when its speed reaches zero.

One of the potential problems with plugging as a braking method (especially when the braking time is short) is that it can be difficult to brake the motor at exactly zero speed. Another drawback to plugging is that it can induce high mechanical shock loads on the motor and connected equipment, due to the abrupt stop that it causes. Plugging is also a very inefficient method of stopping and, therefore, generates significant heat.

Despite these drawbacks, plugging is used in equipment such as elevators, cranes, presses, and mills, where a rapid stop of the motor (with or without reversal) is required.

What is pitch in the context of conveyors?

February 19, 2019 By Danielle Collins Leave a Comment

Roller chains are one of the most common types of transport media for conveying systems. And while they’re available in many designs and variations to meet different application requirements, they all have one thing in common:

To specify a roller chain, you need three basic dimensions: chain pitch, roller diameter, and width between inner link plates.

Roller chains are specified by three main parameters: pitch, roller diameter, and width between inner links. Chains that have identical dimensions in these three dimensions will work on the same sprockets.
Image credit: Kobo USA

In general terms, pitch can be specified with reference to any feature — such as a hole or an edge — that is repeatable on each adjacent part. In terms of conveyor chain, pitch is usually defined as the distance between links, as measured from the center of the roller pin on one link to the center of the roller pin on the next link.

Note that some precision link conveyors refer to the pitch as the “link size.”

: Image credits: Motion Index Drives (top) and DESTACO (bottom)

The pitch of a conveyor chain or link is a determining factor for several performance characteristics of the conveyor. For example, there’s an inverse relationship between sprocket speed and chain pitch. Smaller pitch chains generally allow the sprocket to run at a higher rotational speed.

n = sprocket speed (rpm)

V = chain speed (m/min)

P = chain pitch (mm)

N = number of sprocket teeth

The smaller the chain pitch, the higher the permissible rotational speed of the sprocket.
Image credit: Senqcia

It’s also important to note that the smaller the pitch, the more teeth will be needed on the chain sprocket. And a higher number of sprocket teeth means that more chain links will be engaged during motion. This allows the chain to travel with less speed fluctuation and a smaller articulating angle, producing less vibration and better smoothness of motion. More sprocket-link engagement also provides less wear between the chain bushing and pin, meaning longer life of the chain. For these reasons, manufacturers generally recommend using the smallest chain pitch that satisfies the application conditions.

Wear to the pins and bushings can also cause the pitch to elongate. Manufacturers typically recommend replacing the chain when the extension of the pitch length reaches 2 to 3 percent of the normal pitch value.

Elongation of the pitch length is caused by wear to the pins and bushings. Choosing a chain with a smaller pitch can reduce the amount of wear, and therefore, the amount of pitch elongation.
Image credit: The Diamond Chain Company

When do tubular linear motors outperform traditional iron core and ironless designs?

February 15, 2019 By Danielle Collins Leave a Comment

In a recent post, we looked at traditional iron core and ironless linear motors, both of which have a flat-type construction. But another type of linear motor, often referred to as a “tubular linear motor,” is also gaining traction in industrial applications. This is especially true in the packaging and medical industries, where tubular linear motors have proven an ideal replacement for pneumatics, with a similar form factor but much better efficiency and reliability.

Like their flat counterparts, tubular linear motors have two main parts: permanent magnets and a stator that houses windings. But in the tubular linear motor design, the magnets are not laid out on a flat track; instead, disc-shaped magnets are embedded in a tube (often referred to as a thrust rod), and the stator (also referred to as a forcer) surrounds the thrust rod.

Tubular linear motors can be iron core or ironless types. They offer an alternative to pneumatic and ball screw actuators, with both high speed and high thrust force capabilities.
Image credit: LinMot USA, Inc.

The tubular design has several key benefits over flat linear motors. First, all the magnetic flux from the permanent magnets is harnessed to generate force. And, according to the Lorentz force principle, the force generated by the interaction of the thrust rod magnets and the stator coils is perpendicular to both the magnetic field and the current — in the direction of travel. These two attributes give tubular linear motors extremely high efficiency. This higher efficiency means less heat is generated, so there is less expansion and contraction of components due to thermal effects, and less heat is transferred to the external load. The end result of higher efficiency and less heat generation is better positioning accuracy.

Force production for tubular designs is a linear function of drive current, because the air gap between the stator and thrust rod is non-critical. This means that even if the air gap varies over the length of the stroke, the motor’s force production will remain the same.

Another benefit of tubular designs over flat linear motors is their compact footprint. And tubular linear motors can operate with either the stator (forcer) moving and thrust tube stationary, or with the thrust tube moving while the stator is held stationary. The ability to have the trust tube moving is one of the attributes that makes tubular linear motors a good replacement for pneumatic cylinders, which often operate with an extending and retracting rod, for pushing or pressing operations.

With a tubular linear motor, the thrust rod can move while the forcer is stationary, or the forcer can move while the thrust rod is held stationary.
Image credit: Parker Hannifin Corp.

Like their flat counterparts, tubular linear motors can use iron in the stator surrounding the coils, or they can be constructed with ironless stators. Ironless types produce less force, but don’t experience cogging, so they can achieve very smooth motion, even at low speeds.

Tubular designs with iron in the stator have an ease-of-use benefit over their flat, iron core counterparts because the cylindrical design effectively balances the attractive and repulsive forces between the stator and the thrust rod, so assembly is not as difficult for iron core tubular designs as it is for iron core flat designs. But, like their flat counterparts, tubular iron core linear motors do experience cogging.

What are capacitive proximity sensors?

February 14, 2019 By Miles Budimir Leave a Comment

A basic proximity sensor is used to sense the presence of objects or materials. What differentiates them from other sensors is that they don’t make physical contact with the object being sensed, and hence they’re also known as non-contact sensors.

The diagram shows the internal construction of a capacitive proximity sensor with the internal plate connected to the oscillator (sensor electrodes), and the other being the sensed object, which is detected within the electric field.

One of the most common sensor types is the capacitive proximity sensor. As the name suggests, capacitive proximity sensors operate by noting a change in the capacitance read by the sensor. A typical capacitor consists of two conductive elements (sometimes called plates) separated by some kind of insulating material that can be one of many different types including ceramic, plastic, paper, or other materials.

Typical capacitive proximity sensors, such as those shown here from AutomationDirect, feature variable sensing distances, in this case from 2 up to 40 mm and can sense metal and non-metal objects. They also feature LED status indicators to help easily verify operation and are IP65 and IP67 rated for use in extreme environments.

The way a capacitive proximity sensor works is that one of the conductive elements, or plates, is inside the sensor itself while the other one is the object to be sensed. The internal plate is connected to an oscillator circuit that generates an electric field. The air gap between the internal plate and the external object serves as the insulator or dielectric material. When an object is present, that changes the capacitance value and registers as the presences of the object.

Capacitive proximity sensors are useful in detecting a wide range of objects. The easiest types of objects to detect are ones with a high density (such as metals) or a high dielectric constant (i.e. water). And detecting these objects doesn’t require that the sensors be fairly close to the objects to be detected, another plus if used in settings with little space to work in. Overall, good sensing targets for capacitive sensors include solids and liquids such as various metals, water, wood and plastic.

A typical sensing range for capacitive proximity sensors is from a few millimeters up to about 1 in. (or 25 mm), and some sensors have an extended range up to 2 in. Where capacitive sensors really excel, however, is in applications where they must detect objects through some kind of material such as a bag, bin, or box. They can tune out non-metallic containers and can be tuned or set to detect different levels of liquids or solid materials.

What is an IK rating, and how does it apply to motion control products?

February 13, 2019 By Danielle Collins Leave a Comment

If you deal with electrical components, including electrical enclosures such as control cabinets, you’re probably familiar with IP (International Protection) ratings, which specify the enclosure’s ability to prevent the ingress of solid objects and liquids. But you may be less familiar with the IK rating system, which defines the enclosure’s ability to protect its components from external mechanical impacts, as measured by the impact energy, in joules.

Like IP ratings, IK ratings specify how much protection an enclosure provides for its contents. But rather than protection from ingress of solid objects and liquids, an IK rating indicates the amount of protection the enclosure provides against external mechanical impacts.
Image credit: Hoffmann

A joule is a very small amount of energy. A common example of one joule is the energy required to lift a small apple (100 g, or 0.1 kg) against gravity (9.81 m/s², or approximately 10 m/s²), to a height of 1 meter.

0.1 kg * 10 m/s² * 1 m ≅ 1 kgm/s², or 1 J

Although the units for the joule (kgm/s²) are the same as the units for torque (1 kgm/s² = 1 Nm), a joule is a scalar quantity (it has magnitude only) of force applied through a distance, while torque is a vector quantity (it has both magnitude and direction) of force applied at a distance.

The IK rating was originally introduced as the European standard BS EN 50102 in 1995, but was replaced by the international standard IEC 62262 (and the renumbered European standard EN 62262) in 2002. Prior to these standards, an impact protection rating was often added to the end of an enclosure’s IP rating. For example, IP66(9) would mean the enclosure had an IP rating of 66 and an impact rating of 9. The IEC 62262 standard provides ten levels of protection, designated by two-digit codes, from 00 (no protection) to 10 (highest level of protection).

Image credit: APEM

An enclosure’s IK rating is determined by a testing procedure set out in IEC 62262. The testing procedure involves impacts administered by a pendulum-type device, which uses hammers of various weights to simulate different masses being dropped from increasing distances from the impacted surface. The impact tests, known as “Charpy tests,” are carried out for every surface that is exposed during normal usage of the enclosure. For an enclosure with an area to be tested that is less than 1 meter in length, three impacts are administered. For a tested area over 1 meter in length, five impacts are administered.

The Charpy test simulates the impact of dropping specified weights from various distances.
Image credit: TWI Ltd.

The IEC 62262 standard specifies that the locations of the impacts should follow a certain symmetry and should be distributed evenly over the surface, but the manufacturer has significant discretion in choosing where the impacts are located. And parts such as hinges and locks are excluded from testing. Therefore, it’s important to understand the manufacturer’s testing procedure, as the enclosure’s IK rating can be affected by where the impacts were applied.

In addition to how and where the impacts are administered, IEC 62262 also specifies how the enclosure should be mounted and the atmospheric conditions that should be present during testing. It also provides instructions for the size, dimensions, style, and materials of the hammers to be used for testing.

Note that an enclosure must meet both the stated ratings, IP and IK, together. For example, if an enclosure maintains its IP66 rating after passing the test for IK06 protection, it can be labeled as both IP66 and IK06. However, if, after the enclosure passes testing for IK08 protection, it only maintains IP54 protection, then it must be labeled as IK08 and IP54, or IK06 and IP66, but it cannot be labeled as IK08 and IP66.