How to select aic rating

How to select aic rating. This means that the fuse can interrupt the asymmetrical current associated with this rating. Step 4 – List the SCCR marking on the control panel nameplate (SB5. May 20, 2021 · What is Considered a Good AIC Value? The Akaike information criterion (AIC) is a metric that is used to compare the fit of different regression models. Does this mean that my What is kAIC rating. But a. There is a local, to me, company that recertifies everything. In the formula, L represents the maximized likelihood of the model, which measures how well the model fits the data. You need a short circuit current study to find out how much current is actually available at the machine. The disconnecting means must have a short circuit current rating that is equal to or exceeds the avaliable fault Key Defi nitions: SCCR: “The maximum short circuit current a component, assembly, or equipment can safely withstand when protected by a specifi c overcurrent protective device, or for a specifi ed time interval. Mar 15, 2022 · Ampere interrupting capacity (AIC) refers to circuit breakers and fuses, and when a product shows an AIC rating, it includes circuit protection. Nov 8, 2019 · AIC formula (Image by Author). May 20, 2021 · The Akaike information criterion (AIC) is a metric that is used to compare the fit of different regression models. Not that I know of. The panelboard which I ordered comes standard with 18 KAIC breakers. 110. The 600A rating of the equipment has nothing to do with the available fault current or the AIC rating of the symmetrical interrupting rating at a specific power factor. Here's an introduction. Amp Rating Every fuse has a specific amp rating. UL 489 requires a unique test set-up for Need to assure that the available short-circuit current where equipment is being installed does not exceed the rating marked on the equipment. If the current goes beyond this value, the circuit breaker could be damaged. The lower the AIC score the better. Non-Time Delay Fuse. Aug 24, 2019 · The panel lists the following acceptable breakers: QP, QPH, HQP, HQPH, MP-T, MP-HT. Insulated gate bipolar transistors (IGBTs) are then used to re-create an AC sine wave to provide power to AC induction motors. May 31, 2020 · Score rewards models that achieve high goodness-of-fit and penalize them if they become over-complex. Apr 6, 2010 · An AIC rating is the maximum amount of fault current a breaker is capable of interupting and is determined though ectensive testing by the OEM. An A1C test measures the average amount of sugar in your blood over the past few months. See full list on galvinpower. The AIC is used to compare the goodness of fit of two regression models where one model is a nested version of the other model. Small conductors [Sec Feb 19, 2017 · The AIC rating is on the label of the breaker. Nov 26, 2019 · Put 8 in series for a 24V system and you get 8*. The proper rated replacement breakers take about 30% to 50% more physical space, so it takes some creativity to fit everything. Jun 3, 2009 · The first rating I remember seeing was 5000 AIC. org Mar 26, 2020 · Revised on June 22, 2023. Oct 2, 2023 · Learn all the criteria of circuit breaker ratings to identify the proper circuit breaker that suits your application. All Siemens safety switches have two horsepower ratings for motor applications. There is no limit on higher AIC rating of OCPD. However, each power component within the panel has a different short Circuit Current rating or interrupting rating, most of which are likely to be 5ka or less if a 22 ka fault were to occur, the main circuit protective device may Dec 15, 2012 · Overcurrent protection will have an amperes-interrupting capacity. an interrupting rating of 22 ka, some manufacturers of unapproved panels were labeling the panel with an sCCr of 22 ka. Or are you trying to coordinate the trips on the breaker where a 20 amp does not shut the facility down. 83 (C)], and it is 10,000A for fuses [Sec. 269. The problem is the Dec 21, 2019 · Available short circuit current is the fault current that can be delivered by the utility based on their system. The dataset consists of information of housing prices. Then series rate from there downstream. Calculate your secondary potential and that's your first AIC OCPD rating. Oct 2, 2017 · The short-circuit current rating is the maximum amount of RMS (Root-Mean-Squared) current an electrical component can handle when using an overcurrent protection device, such as a fuse, or for a given amount of time at a specified voltage. The AIC rating of the breaker has nothing to do with the available fault current, other than the breaker rating has to exceed the available fault current. Step 3. For example, you would multiply 150 by 50 to get 7,500 and then divide that number by 1,000 to get 7. 4 (B), 670. A 600kcmil conductor is required. e. It is calculated as: AIC = 2K – 2ln(L) where: K: The number of model parameters. Decide which type of protective characteristic (cable or motor protection). Stepwise can help to choose the best variables to add. M. Jul 6, 2006 · The "AIC rating" is the amount of current that can be dumped into a piece of electrical equipment under short circuit conditions without having [SIZE=-1]shrapnel blown out of the enclosure. Loop in R to select lowest AIC for a statistical model. 1) (8. Mar 14, 2018 · How could I remedy that and is there a way to automate the process directly output the parameters with the lowest AIC value (without having to look for it throught all the possibilities). The standard rating, 10 HP, applies when non-time delay fuses are used. 3 (A)(4). The Akaike Information Criterion (AIC) is another tool to compare prediction models. The search will not cross filter between Countries and There are a few different criteria to consider when selecting a circuit breaker including voltage, frequency, interrupting capacity, continuous current rating, unusual operating conditions and product testing. 60 (C) (3)]. 1) Δ AIC = AIC model − AIC topModel. The infinite bus short circuit current is useful in design to spec the AIC and SCCR equipment ratings. The Akaike information criterion (AIC) is a mathematical method for evaluating how well a model fits the data it was generated from. The surge rating or kA rating of an SPD is one of the most misunderstood ratings. 3) Select beakers/fuses that have an AIC as high or higher than that AFC. Re: How do I apply AIC or Interrupting Rating. For HVAC equipment the rules can be paraphrased as follows: Sep 13, 2019 · I have written some code to select my variables using the F Statistic P value. 2. It matters because if you have a hard fault in your equipment, and you're not rated for at least the AIC available, your equipment can explode and burn, among other things, before the fault is cleared. Fully rated systems can consist of all fuses, all circuit breakers, or a combination of fuses and circuit breakers. kA rating is known as the short circuit withstand capacity or ultimate breaking capacity of a circuit breaker. Explore offers Sep 18, 2021 · Founder of Rubens Technologies, the crop intelligence system. In this article, we will provide a step-by-step . 9 and 110. 2) Select panels that have an SCCR as high or higher than that AFC. This article will give a step by step overview on selecting an appropriate circuit breaker for your specific application. 10, 409. and so provides a value of 0 for the top-ranked AIC model and a measure of how much worse on the AIC scale the other models are. There¡¯s also a tendency to think that the Mar 3, 2020 · If this breaker were operating at 600V it has an interrupting rating of 18,000A, at 480V the rating is 25,000A, etc. Following is more detailed information about each step. At 24v that means the short circuit current is 24/. An example would be a 200-amp circuit breaker or fuse with an ampere interrupting capacity (AIC rating) of 42k AIC or 42,000 amps, installed in a Technical Brief - Short Circuit Current Rating The National Electrical Code (NEC) governs the calculation, product label, and application of SCCR as outlined in articles 110. Do I need to specifically calculate the available fault current at each breaker or am I allowed to series rate the breakers down since I have a fuse of 200 KAIC upstream from them. Mar 19, 2008 · The MLO panel itself will have a short circuit withstand rating. The interrupting rating of a branch circuit fuse is required by Jan 16, 2020 · Overcurrent protective devices must have an interrupting rating capacity equal to or greater than the fault current available at the equipment line terminals [Sec. the potential. The amp rating of a fuse normally should not exceed the current carrying capacity of the circuit. 150A slow-blow) 1) Determine the available fault current. Use this table to initiate the process of identifying the short-circuit current rating of your components and devices in power circuits. Step 2. Nov 29, 2022 · What Is an Akaike Information Criterion (AIC) Score? An AIC score is a number used to determine which machine learning model is best for a given data set in situations where one can’t easily test a data set. Jun 21, 2011 · Selecting the appropriate surge protective device (SPD) can seem like a daunting task, especially with all of the different types on the market today. 004=6000Amps. May 31, 2022 · Terminology is important. The answer is (c), 600kcmil. You don't really run into this very often on run-of-the-mill resi services Spread the loveIntroduction: The Akaike Information Criterion (AIC) is a widely used statistical measure that helps in comparing and selecting the most appropriate model for a given dataset. It used to be like that, but not any more. This rating is key in selecting breakers, as its paramount to provide adequate current breaking power to protect critical system circuitry. , yvar). May 21, 2008. The debates around the use of p -values to identify ‘significant’ effects [ 1, 2 ], Akaike information criterion (AIC) for selecting among models [ 3, 4] and optimal model selection strategies [ 5] are lively, and in some cases divisive. #11. of components incorporated in the feeder and branch circuits. The SCCR rating applies both for individual electrical components and for entire electrical assemblies or Oct 1, 2008 · A 100,000 AIC rated switchboard usually is specified. 10. I and I assume many others would check all the breakers in a panel. 480V class breakers for instance are now becoming somewhat standardized on 35k, 65k and 100k, but some manufacturers have 14k, 22k, 25k, 30k, 50k, 85k etc. Jun 17, 2007 · 06-17-2007, 01:03 PM. Apr 15, 2024 · Input the System Voltage (V), which is the voltage level at which the system operates. Identify 2. For instance, if a conductor is rated to carry 20A, a 20A fuse is the largest that should Jan 9, 2018 · Occupation. AIC means "Amps Interrupting Capacity", the k is shorthand for thousand. 3. I brought that specific section for the PE since they always ask a few of those questions. In lieu of a consensus on these ongoing debates, we avoid the inherent theoretical and Mar 14, 2024 · To calculate the kVA rating for a single-phase transformer, you’ll need to multiply the required input voltage (V) by the required current load in amperes (l) and then divide that number by 1,000: V * l / 1,000. each ses being served from this transformer needs to be braced for this fault current level. then use this total ses amp figure to find the appropriate fault current using, table 800. AIC rating itself has no direct bearing on it. There¡¯s also a tendency to think that the When the AFC goes up from the values shown on the approved plans because of less resistance in a shorter run of wire, equipment AIC ratings may need to be increased in order to comply with NEC ® 110. If you’re looking at a Milbank meter main, the AIC rating only applies to the breaker inside the meter main while the SCCR applies to the entire meter main. Jan 9, 2018. 240. On the labels of most electrical panels will be the following wording or equivalent: “THE SHORT-CIRCUIT CURRENT RATING OF THIS PANELBOARD IS LIMITED TO THE LOWEST AIC RATING OF ANY INSTALLED CIRCUIT BREAKER”. Determine ampacity per parallel conductor, 1200A/3 = 400A. SCCR. . This is the lowest AIC possible, so it is the best model, so the variable you should drop is C2004. ratings. 9, 110. Dec 1, 2000 · A. Determine. , xvar) onto resale price (i. Once there, click on the “free access” tab and select the Current Rating or SCCR. 10kAIC) Overcurrent protection will also have operating rating (e. x May 20, 2021 · The Akaike information criterion (AIC) is a metric that is used to compare the fit of several regression models. The term k represents the number of parameters in the model, including the intercept and any additional predictors. The maximum current a breaker can interrupt without damaging itself is called the Kilo Ampere Interrupting capacity or kAIC for short. See the actual NEC ® text at NFPA. All of the circuit breakers at the main switchboard, including the main and the distribution circuit breakers, have the same AIC rating of 100,000. Select a conductor using Table 310-16 that has an ampacity of 400A at 75øC [Sec. The fuses or the breaker must have an AIC rating equal to or greater than the available fault current at the disconnecting means. Only the nomenclature moves from AIC to the more widely accepted SCCR. AIC is calculated from: breaker marked with an interrupting rating of 22,000A may in fact have an interrupting capacity of only 9,900A. Step 1 – Determine the short circuit current rating of each component in the power circuit Dec 28, 2010 · 1. You will have resistance in your bus bars so lets multiply that by 2 to get a pack resistance of 2 mOhm as a first approximation. The number describes the maximum fault current that the circuit can clear safely with the welding closed or causing damage to personnel or equipment. ”. 1). Sep 6, 2021 · Terminology: AFC = Available fault current is the maximum current that could realistically occur at a given position in your service. As I understand it, BIC penalizes models more for free parameters than does AIC. Unless you know the available fault current, it's difficult for you to determine the AIC of the device you should be using. 22, 409. For thermal damage, you need to compare that separately on the TCC. Geico, Amica and Progressive are among the best car insurance companies in 2024, according to Bankrate’s research. Mar 13, 2015 · The Main fused disconnect has (3) 400 amp fuses that have an AIC rating of 200,000 amps. If your goal is to get accurate predictions, I'd suggest cross-validating your model by separating your data in a training and testing set. Go back to CB Selection Tips ↑. etc. For example, if the MCB is rated at 10kA, it means Dec 1, 2000 · A. 13. Feb 7, 2020 · There is no "AIC" (Amps Interrupting Capacity) rating on a device that is not an "Interrupting" component. ). retired electrician. AIC combines model accuracy and parsimony in a single metric and can be used to evaluate data processing pipelines or variable selection methods. The following should be considered when specifying and installing a VFD:99981231160000-08'00'. As mentioned, it also depends upon the voltage class and amperage range you are speaking about. The transformer feeds a 1200 amp disconnect that is fused at 700 amps supplying an 800 amp, 3-phase 480/277 volt panel used for the temporary on a new building under construction. If the value you want to use is not displayed, select Custom and use the field below to enter the value. Sep 27, 2023 · 1. If it is not on the labeled, then the breaker must be considered to be 5KAIC. This tells us how likely the model is, given the data. Jul 28, 2020 · This equipment usually arrives with 5k to 10k AIC breakers. a measure of model complexity). Click the “Calculate” button to obtain the AIC Rating. g. Step 1. No trees were killed in the sending of this message, but a large number of electrons were terribly inconvenienced. In the series rating method, the main breaker would have an AIC rating of 100,000, but the distribution breakers on the main switchboard can Step 2. A good class T fuse should handle that just fine. How that is accomplished varies depending on what type of breaker you are refering to. The interrupting rating of a passive device such as a lighting contactor is the amount of current that the contactor is rated to interrupt. 9]. Your AIC rating of the primary has no bearing on downstreaming the fault protection on the secondary. The default value of K is 2, so a model with just one predictor variable will have a K value of 2+1 = 3. For proper protection and compliance with National Electrical Code (NEC) 110. Interrupt Rating (IR): “The highest current, at rated voltage, that a device is intended to interrupt under standard test Mar 3, 2013 · IF WE HAVE TO SELECT ACCORDING TO BREAKER SIZE. To summarize, ETC is making this label change to more accurately describe the proper rating of racks, aux bays, and dimmer modules using SCCR rather than AIC. Most VFD manufacturers have 'listed' series ratings with specific protective devices. Aug 30, 2017 · Hello, I have an issue where the fault current at my 480V 3 Phase panel is 24,200A and the rating of the panel itself is 22,000 AIC, but the main breaker has an interrupting rating of 35,000 AIC and the branch circuit breakers have interrupting ratings of 25,000 AIC. For listed low voltage fuses, Jan 22, 2019 · In this episode, we explain how to use the Akaike Information Criterion (AIC) to pick the model with the best generalization performance using only training data. Use the appropriate “Series Equipment Rating” column equal to, or greater than, the available fault current, to determine the allowable UL recognized combinations of main (upstream) and branch (down-stream) overcurrent devices. This is also incorrect. of current-limiting devices in the feeder circuit to increase the SCCR of branch circuit components. Dec 4, 2015 · Select the appropriate circuit breaker type, with or without the thermal overload protection. Note: Selecting a country, a state or province will return all companies matching any of the selections. Package… Feb 15, 2017 · It has an impedance rating of 3. Device clearing time depends on the device settings, the fault current and the shape of the TCC. If the design calls for 22K breakers, you gotta put them in. ORG for the complete code section. But what is an Interrupting Rating? The 2020 NEC (National Electrical Code) defines Interrupting Rating as: The highest current at rated voltage that a device is identified to interrupt under standard test conditions. Oct 1, 2012 · The selection of the protective device is based on the system design and available fault current. Jun 9, 2021 · Have you ever wondered why breakers have two amperage ratings? What's the difference between the one on the side that says "Interrupting Rating" and the one In a Fully Rated system, all overcurrent devices are fully rated for the maximum amount of available fault current (AFC) at their line terminals which complies with the code language in NEC ® 110. By incorporating both the likelihood and the Jun 21, 2011 · Selecting the appropriate surge protective device (SPD) can seem like a daunting task, especially with all of the different types on the market today. 25 = 2mOhm, but if it is a 2P8S it is 1mOhm. Aug 18, 2010 · Use the AIC Rating field to set the rating for the device. It is often more complicated than simply looking at fuse let-through values only. Healthcare providers use it to help diagnose prediabetes and Type 2 diabetes and to monitor how well your diabetes treatment plan is working. Unless marked otherwise, the ampere interrupting capacity (AIC)rating for circuit breakers is 5,000A [Sec. Apr 19, 2023 · The Akaike information criterion (AIC) is a metric that is used to quantify how well a model fits a dataset. A number of typical options are listed. Nov 10, 2023 · The formula for AIC is as follows: AIC = -2 * log (L) + 2 * k. Thus only the symmetrical component of short-circuit current need be considered to determine the necessary interrupting rating of a low voltage fuse. In selecting the amp rating of a fuse, consideration must be given to the type of load and code requirements. Mar 20, 2024 · Step 3 – Determine overall short circuit current rating for industrial control panel (SB4. Customers commonly ask for an SPD to protect their 200A panel. (e. Yes, that shows how to calculate available short circuit current between two points. how to loop through multiple models to put in a list in R. Almost every breaker or fuse manufacturer has an on-line calculator you can use. This information has to come from the utility. KAIR is the equivalent term for fuses. The HQP at 65 kA is three times the price and presumably overkill. So if a breaker says it is 65kAIC, that means it can survive the physical forces that take place when interrupting a fault current level of 65,000 Amperes and One reason one might not select the model with the lowest AIC is when your variable to datapoint ratio is large. Find quotes for your area. The feeder OCPD must have an ampacity not less than the rating of the OCPD (1200A). to calculate equipment SCCR. It takes into account both the goodness of fit and the number of parameters present in the model, aiming to choose a model with minimal information loss. Motivation. The QP and MP-T have a 10 kA AIC, and the QPH has 22 kA and is only about $15 more than the QP. ΔAIC = AICmodel −AICtopModel (8. Select the appropriate table using the system voltage. The utility company had given me the AIC at the secondary side of the transformer (13021). To better understand this, it is necessary to review the standard interrupting rating test procedures for circuit breakers: Molded Case Circuit Breakers - UL 489 and CSA 5 Test Procedures. The panelboard had circuit breakers from different manufacturers as well as both 10k AIC and 22k AIC circuit breakers. 4 days ago · Updated May 29, 2024. The AIC rating is the highest amount of current that the circuit breaker has been tested to interrupt before the circuit breaker fails or possibly explodes. ln(L): The log-likelihood of the model. FWIW, I can't remember putting a 10k AIC on a secondary side. The calculator applies industry-standard formulas and considerations to determine the AIC rating based on the provided fault current and system voltage. 81% and according to the EOR he has based the calculated fault current at 31,570 amps assuming an infinite buss. Sep 18, 2015 · The primary and secondary are always calculated separately on an SDS. 110, 440. Given that this is a service entrance, I assume the amount of short-circuit current available from The AIC and BIC are both methods of assessing model fit penalized for the number of estimated parameters. The interupting rating of an overcurrent device is generally its AIC rating. These ratings generally range from 5 to 200K AIC. May 21, 2008 · Electrical Engineer. For example, a switch might have a standard rating of 10 HP , and a maximum rating of 30 HP. You calculate the amount of available short circuit amps (SCA) then you select an AIC rating that is larger than your result. Sorting ARIMA AIC in R. 9. Mar 14, 2024 · To calculate the kVA rating for a single-phase transformer, you’ll need to multiply the required input voltage (V) by the required current load in amperes (l) and then divide that number by 1,000: V * l / 1,000. Compare rates. 2. I would say it's more typical to use something like SKM or ETAP to do the calculations during design. 8. WHAT IS THE TECHNICAL REASON. Small conductors [Sec The interrupting rating is defined in the NEC ® as “ the highest current at rated voltage that a device is identified to interrupt under standard test conditions . A rule of thumb is that a 2 unit difference on AICs (ΔAIC = 2) ( Δ AIC = 2) is moderate evidence of a difference in the Apr 17, 2003 · My inspector is requiring me to provide the AIC at the main breaker on a 100 amp, residential service. Lower AIC values are still better, both in the Wikipedia article and in the video. Thanks ! python-3. KAIC is kilo amps interrupting capacity, which is the maximum amps that a breaker can withstand and trip safely without catastrophically failing. The plant electrical system fault current usually is 40k to 50k. 110-14(c)(2)(b)]. 4. Using your example you would need to know the trip curve of the main breaker/fuse, then the feeder breaker/fuse for each panel, length, size and type of wire to the panel. Using the rewritten formula, one can see how the AIC score of the model will increase in proportion to the growth in the value of the numerator, which contains the number of parameters in the model (i. The circuit breaker may have an AIC rating higher than the overall SCCR, but the SCCR cannot be higher than the circuit breaker AIC rating. Let’s recollect that a smaller AIC score is preferable to a larger score. Search AM Best's extensive database of life/health, property/casualty insurance companies worldwide and access Best's Credit Ratings, Best's Credit Reports and other key information. A fully rated system is one in which all of the overcurrent protective devices have an individual interrupting rating equal to or greater than the available short-circuit current at their line terminals per 110. Dec 15, 2022 · The. If they are all close to each other in their AIC rating, I would buy a new breaker that matches that. The numerical values of these ratings, some of the highest in the industry, will not change. Both might be rated at 10K, but for AIC that When specifying transfer switches, it is important to understand their Withstand and Closing Ratings so the most appropriate models can be specified. 10, the SCCR of equipment must be equal to or greater than the available short-circuit (or high-level ground fault) current where the equipment is installed. The service drop is approximately 40 feet of #2 alumminium. These are electro-mechanical ratings that assess the device’s ability to maintain integrity if a fault condition occurs downstream of the protection device. In statistics, AIC is used to compare different possible models and determine which one is the best fit for the data. This is referred to as “dual horsepower rated. jraef (Electrical) 3 Mar 13 21:11. Nov 28, 2023 · Running a regression model with too many variables – especially irrelevant ones – will lead to a needlessly complex model. Most of them take into consideration the conductor insulation as well as the material of the raceway. Regardless of cost, you can't mess with AIC. The precise semantic interpretation of the Akaike Information Criterion (AIC) is provided, explicit assumptions are provided for the AIC and GAIC to be valid, and explicit formulas are provided for the AIC and GAIC so they can be Feb 18, 2010 · The VFD needs to have a SCCR rating (AIC ratings are only for protective devices) that is greater than the available Short Circuit Amps (SCA) at its line side terminals. In the middle of the video, the presenter walks through reading the output and shows that dropping C2004 would lead to a new model with AIC = 16. The long answer would take a few hours. Beyond a preference based on the stringency of the criteria, are there any other reasons to prefer AIC over BIC or vice versa? Feb 11, 2020 · kA rating of an MCB or an MCCB is the maximum current it can safely interrupt in case of a short circuit. I would appreciate any information about Oct 1, 2012 · Breakers with higher AIC ratings have upgraded parts to increase the fault current interupting capability, which costs more to do. #4. Common probabilistic methods are: ~ AIC (Akaike Information Criterion) from frequentist Sep 27, 2010 · Interrupting rating is part of the overcurrent protective devices rating not the disconnect rating. instead of using minpv to select my variables, i would like to use the AIC to select the variables. But as Jim says, if the panel is actually being sold with breakers in it, then the interrupting rating of the breakers is for all practical purposes the 'AIC of the panel'unless someone is really dumb and puts breakers of high AIC in a panel that itself has low SCCR Oct 1, 2007 · Specifiers often use the terms short-circuit current rating (SCCR) and interrupting rating (IR) interchangeably. A circuit breaker with a 200- ampere rating for example will not trip unless more than 200 amperes of current is drawn through the circuit breaker. The PSCC level can have a significant thermal impact on the VFD’s diodes and capacitor bank. i am planning to regress the variables (i. There is no formula. Another common misconception is that the circuit breakers AIC rating means that whatever is supplied by the circuit breaker is protected up to the marked AIC rating. 4 steps. After everything above is said. There is a "withstand" rating, which is now what we call the "SCCR" (Short Circuit Current Rating" and in the case of many Non-Fused Disconnects, it is 10kA or less without fuses, basically useless in most industrial applications. An AIC test is most useful when you’re working with a small data set or time series analysis. Note that model selection and prediction accuracy are somewhat distinct problems. Electrical distribution system components such as circuit breakers, panelboards and fuses are assigned fault amperage interrupting capacities, or Available Interrupting Current (AIC) ratings. 5 kVA. also, ensure the new building plans indicate on the one-line the proper bracing or aic rating for the equipment. fl ih nj nz br iu op mr kd th