ATOM INDONESIA JOURNAL Author's Responses
Article : #406
Name of All Authors : Syaiful. Bakhri, Nesimi. Ertugrul
Article Title : An Online Non-Invasive Condition Monitoring Method for Stepping Motor CRDM in HTGR
E-mail : [email protected]
Line # Referee’s Comments Author's Responses
11 Abstract: Please modify the abstract to describe the
manuscript comprehensively! Has been changed
11 Abstract: respectively - > respectively Has been changed
11 Cold -> Cooled Has been changed
30-51
Please describe clearly in details the issues of CRDM for HTGR as the background of the study!
The issues of CRDM HTGR is due to the high temperature, helium environment, and high radiation exposure. Therefore current HTGR (HTR-PM, HTR-10, HTTR-30) using electric motor based CRDM. Especially for two newest reactor (HTR-10 and HTR-PM), stepping motor is chosen due to better safety compare with the HTTR-30 AC motor CRDM. I am saying in introduction.
“Recent development of the CRDM in HTGR can be found in the new reactor such as HTR-10 (10MWth), HTTR-30 (30MWth) and HTR-PM (200MWth). Issues of the research and development in CRDM HTGR mainly focus on the design and technique to overcome the effect of high temperature, helium environment, as well as high radiation exposure. Research in [6] shows that temperature and radiation field inside the pressure shells containing CRDM of HTR-10 may reach 150 oC and 7.61 Sv h-1 respectively. In case of HTTR-30, the maximum allowable temperature services inside the standpipe of CRDM was maintained below 75 oC [7] by indirect air cooling outside the standpipes as well as by injecting small amount cold Helium known as purge gas inside the standpipes. For the HTR- PM, the temperature ambient of the CRDM under long-term of radiation exposure is 150-250
oC[8]. Because of these ambient conditions, electric motor type of CRDM is more suitable than the magnetic coils, pneumatic, hydraulic drive. “
52-63
Please explain in details the current status of CRDM for HTGR (e.g. HTR-10 and HTR-PM) to make the study clearer!
I do explain in introduction the current status of CRDM which is only found in new HTGR reactor. This current status is also the answer of the current detail issues of CRDM HTGR (line 52-63).
“The current status of electric motor based CRDM in HTGR is that the stepping motor is employed for the HTR-10 [6] and HTR-PM[9], and the alternating current motor is for the HTTR-30 [7, 10]. The stepper motor has been identified to have a better safety due to the omission of traditional counterweight or brake clutch [6, 8]. The stepper motor also has high accuracy, fast response, simple control as well as simple kinematics which significantly contribute to its high reliability [6, 8]. Therefore, this paper focuses on the stepper motor based CRDM”
374- 378
615- 620
585- 592
Have you done validation or benchmarking the method with the standard/real case? How can you make a statement that the method is appropriate / fit for HTGR?
Validation was done to confirm the effectiveness of the method to detect the common faults in CRDM (refer to previous line 251-260). One of the case, high-resistance problem is exposed in this paper
“This simulated fault is employed to demonstrate the applicability as well as the validation of this method in identifying the common fault problems of CRDM as given in the previous section.”
This validation is not enough for the real CRDM, therefore We’ve explained further research suggestion in conclusion.
“Future research should consider further complete validation and verification of the method for real CRDM HTGR. In addition, other types of electrical related faults, such as winding motor faults, or rotor faults, as well as the mechanical related faults can be investigated.”
I do very sorry, I could not find the exact statement saying that the “method is appropriate/fit for HTGR” in my original paper. However, I have revised this paper to accommodate the suggestion in the conclusion part by saying that this approaches of non- invasive monitoring can be applied for CRDM HTGR. Very appreciate for the correction.
“It can be concluded that the online non-invasive monitoring technique based on the supply voltage, stator current, and torque monitoring demonstrates an approach which can be applied for a noninvasive condition monitoring technique of CRDM HTGR.”
We do believe that this approaches works for stepping motor CRDM HTGR fault detection monitoring because we demonstrated the basic concept of online monitoring of stepper based CRDM as well as the applicability. Further development of online monitoring based on the pattern matching undoubtedly is required to really deploy this method for the real CRDM HTGR
130
Please explain how the method can identify the component degradation due to the corrosions
! What kind of corrosion? Please describe and explain clearly!
This paper now highlighted the common connector problem, which is indicated by the high-resistance connection. Corrosion is only one of causes which affect the high resistance problem. Here I am saying,
“To see the effectiveness and the applicability of the proposed method, a case study on the simulated asymmetrical supply problems is provided. The asymmetrical supply problems can be caused by high-resistance connections between the circuit driver and the electric motor [18, 19]. It was pointed out in [20] that the high- resistance connections can be produced by contact surface contamination, corrosion/oxidation of the connectors, pitted/worn/rough connector surface, under/overtightening of connectors, mismatch between connectors, or looseness of connectors due to vibration and thermal cycling.”
Half of the references are published more than 5 years ago. Please refer the current literatures (80% of the references should be published within 5 years with at least 10 literatures).
13 recent publication no more than 5 years
109- 112
585- 616
Please revise/improve the conclusion to make clear the relation between the purposes of the study (to propose a new method of the CRDM for HTGR) with the results!
The Purpose: “This study aims to address the challenges (mentioned from line 92 to 107) by demonstrating a non-invasive online monitoring method which can be applied for the CRDM in HTGR.”
The purpose is then answered in conclusion:
“It can be concluded that the online non-invasive monitoring technique based on the supply voltage, stator current, and torque monitoring demonstrates an approach which can be applied for a noninvasive condition monitoring technique of CRDM HTGR. The patterns of voltage output signals in each block components of CRDM are compared to determine the healthy and faulty states of the motor. The knowledge of the control pattern from output of the logic generator as well as the generated supply voltage signatures are the key feature for condition monitoring method. The measured stator current and torque are also further signatures to determine the severity and effect of the faults of stepping motor CRDM.
The proposed online non-invasive condition monitoring method successfully identifies the poor connection problem using high-resistance approaches based on measured voltage, stator current which is used also for the torque analysis. It was found that 2.9% increase in resistance results in 5.1% and 3.3 % reduction in current and torque values respectively. The method also provide signatures of healthy motor, such as mutual inductions of the motor’s winding in voltage and current measurement, the effect of moment inertia, the effect of speed variation, time constant and torque which can be used to
identify any abnormalities in the drive.”
References should be written as the guidance/role
of Atom Indonesia Journal. Has been changed
Please return to Atom Indonesia Editorial Office via e-mail: [email protected] and Faximile: 021-7560895.
This original sheet should be returned to:
Tata Usaha Atom Indonesia, PPIKSN-BATAN, Gedung 71, Lantai 1, Kawasan Puspiptek Serpong, Tangerang, Indonesia 15310
Author Signature(s) Date, 28 August 2015
Syaiful Bakhri
ATOM INDONESIA JOURNAL Author's Responses
Article : #406
Name of All Authors : Syaiful. Bakhri, Nesimi. Ertugrul
Article Title : An Online Non-Invasive Condition Monitoring Method for Stepping Motor CRDM in HTGR
E-mail : [email protected]
Line # Referee’s Comments Author's Responses
92-107
You mentioned: “However, the online monitoring method as well as the fault detection have not been investigated more detail. Therefore, based on the previous reality of research, this study is aimed to address these challenges by proposing an online monitoring non-invasive method to identify degradations or faults of the CRDM in HTGR”.
(original line 83-90)
To make this part clearer, you should describe:
How current online monitoring methods
implemented in HTGR and what problems are exist
How fault detections are currently performed in HTGR and what problems are exist
Then you can claim that you want to address these challenges.
Unfortunately, in current state, I cannot see the challenges and the contributions of your research.
We have rewritten most part of this paper to be more precise and clear in statement. Now we are saying that the online monitoring methods of stepping motor CRDM have not been implemented in HTGR. No literature has been found saying exactly the online
monitoring for the CRDM of HTGR. We are very appreciate for the correction. The statement now is :
“However, these previous cited works have not studied the implementation of online condition monitoring system of stepping motor of the CRDM in HTGR. In [14, 15]monitoring circuit model was used for the protections purposes only, not used for the condition monitoring purposes with the capability to identify symptom of faults or component degradations.
Furthermore, the previous stepper motor based CRDM in PWR [11-13], has not considered the condition monitoring. An effective model in such system, should consider the degradations in system as well as the potential faults. In addition, the previous works in [9, 16, 17] only emphasize the control of CRDM not consider for further implementation of fault detection and online monitoring.”
119- 143
You mentioned: “This paper demonstrates the condition motoring method of stepper
motor-based CRDM through several detail steps.
Firstly, online condition monitoring
of the logic patterns control is carried out, followed by the stepper motor driver block.
Secondly, a case example in online detection of motor’s faults due to corrosion
problems based on measured voltage, stator current and torque is also investigated.
These steps are carried out to ensure that the proposed online non-invasive method
covers all components as well as to ensure the applicability of the method for condition monitoring purposes.”
This part is not clear. You should say, for example:
Many thanks for the suggestion. We have rewritten according to the suggestion (line 119-143).
“This paper describes the proposed Online Non- Invasive Method to monitor the condition of stepping motor CRDM in HTGR. The online non-invasive method consists of online acquisition of the output electric signals of each block component of the CRDM, followed by signal pattern matching based on its shape and timing between each block. The key of this online monitoring method is to identify the signature differences of the measured supply voltage, electric current signals including the produced torque between the healthy and faulty motor. To see the effectiveness and the applicability of the proposed method, a case
349- 383
“This paper describes the proposed Online Non- Invasive Method to monitor the
condition of stepping motor CRDM in HTGR. The proposed method consists of
……..or The proposed method applies …… to…. and
…. to …… To see the
effectiveness and the applicability of the proposed method, a case study on …… is provided.”
Then you provide one Section to describe steps of your proposed method in details to enable readers following and applying the proposed method.
study on the simulated asymmetrical supply problems is provided. The asymmetrical supply problems can be caused by high-resistance connections between the circuit driver and the electric motor [18, 19]. It was pointed out in [20]
that the high-resistance connections can be produced by contact surface contamination, corrosion/oxidation of the connectors, pitted/worn/rough connector surface, under/overtightening of connectors, mismatch between connectors, or looseness of connectors due to vibration and thermal cycling.
We write the section describing steps of the online monitoring methods in experimental section (line 349-383).
“The online non-invasive monitoring methods is carried out in the following steps. The online monitoring system acquires output voltage and current signals of the logic generator unit (PLC) and motor driver unit (H-Bridge) simultaneously.
These voltage and current signals are investigated to understand the healthy signature of each unit. The fault detection of online monitoring is done by comparing the output voltage pattern of the motor drive unit to the generator unit, called pattern matching. This pattern matching is also synchronized with a standard clock signal to confirm any phase failures. This paper demonstrates this pattern matching with the wave drive, full drive and half drive logic pattern cases both for clockwise and counter clockwise rotation direction.
Furthermore, the measured motor stator current and calculated torque can be also examined to confirm the signatures of the stepper motor faults as well as the effect of stepper motor loading which are not easily identified through measured voltage assessment only. The faults due to high- resistance connector between the motor driver and the stepper motor are also simulated using the external resistor as shown in Fig. 3. This simulated fault is employed to demonstrate the applicability as well as the validation of this method in identifying the common fault problems of CRDM as given in the previous section. It should be noted that this basic method can also be applied for other purpose of electric motor monitoring. Detail implementation of this online monitoring for CRDM is discussed in the following section”
I cannot see any information on a typical HTGR CRDM. Why do you proposed your
method for HTGR only?
We mentioned the typical CRDM in line (169- 198). This is the typical CRDM which can be found in HTR-10 and HTR-PM, the newest HTGR reactor. The information covers important parameters for the CRDM which are important for this research. Here is the paragraph.
169- 198
34-51
“Fig. 1 shows one of the examples of CRDM for the HTGR type power plant (HTR-10) [6]. Note that, the control rod drive mechanism has a stepping motor, a magnetic damper, and a gear box, a sprocket wheel, a worm-gear reducer and control rod position detection system. The stepper motor provides a rotating force to lower and withdrawn control rod at certain speed of rotation. The requirement of control rod insertion speed for the HTR-10 is 10 mm s-1 or equal with 30 rpm with the emergency insertion less than 8s.
Another component such as magnetic damper which requires no electricity to generate damping torque is employed to reduce the speed during the free fall emergency insertions for no more than 0.8 m s-1 and to minimize any shock energy at the end buffer of control rod. The above speed requirement is also implemented to accommodate the maximum allowable speed of the sprocket wheel. The gear box is employed to reduce the speed from the 30 rpm into 3 rpm and also increase the applied torque. To measure the position of control rod, a worm-gear reducer is employed between the sprocket wheel device and the synchro. The total rotation of the synchro for 282o indicates a whole stroke for the movement of control rod. Such CRDM is controlled by an arrangement which consist of a stepping motor driver, a pulse signal generator, an MS4405 counter–timer interface and a computer.
We only propose for the HTGR because the current type HTGR employs stepping motor based CRDM to overcome the environmental condition “high temperature, helium environment, and high radiation exposure”, we say this in introduction (34-51). Other approaches such as using vibration or acoustic emission might not suitable under such high extreme condition which might not be found in other reactor type.
“Issues of the research and development in CRDM HTGR mainly focus on the design and technique to overcome the effect of high temperature, helium environment, as well as high radiation exposure. Research in [6] shows that temperature and radiation field inside the pressure shells containing CRDM of HTR-10 may reach 150 oC and 7.61 Sv h-1 respectively. In case of HTTR-30, the maximum allowable temperature services inside the standpipe of CRDM was maintained below 75 oC [7] by indirect air cooling outside the standpipes as well as by injecting small amount cold Helium known as purge gas inside the standpipes. For the HTR- PM, the temperature ambient of the CRDM under long-term of radiation exposure is 150-250
oC[8]. Because of these ambient conditions, electric motor type of CRDM is more suitable than the magnetic coils, pneumatic, hydraulic drive.”
56-62
In terms of electric motor applications between HTR-PM (stepper motor) and HTTR-30 (AC electric motor), the stepper motor itself has more advantageous than the AC/DC electric motor.
We do say in line 56-62:
“The stepper motor has been identified to have a better safety due to the omission of traditional counterweight or brake clutch [6, 8]. The stepper motor also has high accuracy, fast response, simple control as well as simple kinematics which significantly contribute to its high reliability [6, 8].”
Therefore, we propose this indirect online noninvasive monitoring using voltage and current measurement for the stepper based motor CRDM application in HTGR.
280
I cannot find any discussion, which is specific on HTGR CRDM.
The experiment is not applied for real CRDM.
It has been mentioned in experimental method that I do use a CRDM stepping motor based simulator. (line 277-285)
“In this paper, the experiment is focused on stepper motor including the logic generator and power driver as the typical required component in CRDM of HTGR. This simple CRDM stepping motor based simulator arrangement is sufficient to demonstrate the common faults of typical CRDM components, i.e. logic generator section, power driver section and cable connectors, as mentioned in theory section.”
The recent CRDM simulator we had is an arrangement consist of logic generator, motor driver and stepping motor with the 4 phase connectors. This arrangement is enough to represent a stepping motor drive mechanism in CRDM for a normal condition as well as faulty condition such as the faults in logic generator, faults of motor drive, fault of connector, faults, winding of stepper motor, rotor of stepper motor, alignment to control rod, etc. Therefore, further discussion in Results and Discussion section is sufficient to be focused on these component arrangement as the main part of CRDM HTGR. The discussion in Result and Discussion section was then carried out to understand the normal condition of this CRDM, to understand the faults and how the fault (in this case the high- resistance connector) can be differentiated from the normal condition.
You claim: “It can be concluded from the research that the proposed monitoring technique based on the supply voltage, stator current, and torque give a
I do revised this paper to accommodate the suggestion by saying in conclusion part that this approaches of non-invasive monitoring
585
comprehensive approach for the condition monitoring of CRDM HTGR without stopping and
damaging the motor.”
How can you come to such conclusion?
can be applied for CRDM HTGR. Yes, this methods can be applied during the stepper motor’s operation (without stopping motor) and without damaging the motor (no need to dismantling the motor to look for the exact fault of components). This non-invasive technique is common in condition monitoring of electric motor but the application for the stepper motor especially for the CRDM is not found in literature and considered relatively new.
“It can be concluded that the online non-invasive monitoring technique based on the supply voltage, stator current, and torque monitoring demonstrates an approach which can be applied for a noninvasive condition monitoring technique of CRDM HTGR. The patterns of voltage output signals in each block components of CRDM are compared to determine the healthy and faulty states of the motor. The knowledge of the control pattern from output of the logic generator as well as the generated supply voltage signatures are the key feature for condition monitoring method. The measured stator current and torque are also further signatures to determine the severity and effect of the faults of stepping motor CRDM.
There is a standard approach for proposing a method, i.e. description on steps of the proposed
method, illustration on how the proposed method to work and validation using a case study to show the applicability of the proposed method to solve the defined problem. Finally, the advantageous and the weaknesses of the proposed method are described.
Hence, based on your title, I expect your manuscript to describe steps of the Online Non-Invasive Method to monitor the condition of Stepping Motor CRDM.
To validate the method, you then provide a case study to monitor the condition of the Stepping Motor CRDM in HTGRand benchmark the results. To emphasize the applicability of your proposed method, you can describe the advantageous offered by your proposed method. Unfortunately, I cannot see all of these standard approaches in your present manuscript.
The steps of the online monitoring approach as well as the fault condition case study are described in experimental method. The illustration of hardware arrangement is also described in the experimental method section.
The case study of high-resistance fault is selected to show the applicability of the method. Detail implementation of this method is presented through the result and discussion section. The results and discussion section demonstrates finding which should be highlighted for the online monitoring implementation. The examples are in the following statements.
“Fig. 6 shows the pattern matching between the output signal of logic generator unit and the output signal of motor driver unit.” (line 428)
Another signature of pattern signal, the voltage signals have a small overshoot at the beginning of the step, as well as undershoot followed by a small oscillation at the end of a step, as shown in Fig 6. (line 444)
“Fig. 6 also indicates out the possibility to monitor the effect of mutual induction between two active poles.” (line 489)
“The information of stator current can be very useful to represent the online torque disturbances or motor faults during the CRDM operations”.
The investigation is required to understand the behavior of measured of voltage and current as a function of speed.
“The voltage and stator current measurement also show that condition monitoring of CRDM should consider all phases of the stator.” (line 513)
“The condition monitoring also demonstrates a detection of high-resistance connectors which can lead to a fault in CRDM.” (line 522)
Fig. 9 also shows the rate of increase and reduction in stator current in each step. Note that the current variation is affected by the ratio of the inductance and the resistance of the winding (L/R), known as the time constant of the stepper motor (T0). (line 537)
The high-resistance problem also affects the torque as shown in Fig. 10 (c). (line 558)
A case study to validate the applicability of this method is implemented under high- resistance fault (line 130-143).
“To see the effectiveness and the applicability of the proposed method, a case study on the simulated asymmetrical supply problems is provided. The asymmetrical supply problems can be caused by high-resistance connections between the circuit driver and the electric motor [18, 19]. It was pointed out in [20] that the high- resistance connections can be produced by contact surface contamination, corrosion/oxidation of the connectors, pitted/worn/rough connector surface, under/overtightening of connectors, mismatch between connectors, or looseness of connectors due to vibration and thermal cycling.”
In case of benchmark result, further validation and verification is required. We say in the conclusion
“Future research should consider further complete validation and verification of the method for real CRDM HTGR. In addition, other types of electrical related faults, such as winding motor faults, or rotor faults, as well as the mechanical related faults can be investigated.”
The advantages of this method is explained in line 111-118
“This method provides the assessments of CRDM to identify normal, degradations as well as faults without stopping the control rod control system in continuous manner and without direct access to the motor. This method will be beneficial for wide range of stepper motor applications even though the HTGR application
is the focus in this paper.”
The advantages of this method to indicate the signature of the motor which can be applied for the indicator of the online monitoring is also explained in the conclusion
“The proposed online non-invasive condition monitoring method successfully identifies the poor connection problem using high-resistance approaches based on measured voltage, stator current which is used also for the torque analysis.
The method also provide signatures of healthy motor, such as mutual inductions of the motor’s winding in voltage and current measurement, the effect of moment inertia, the effect of speed variation, time constant and torque which can be used to identify any abnormalities in the drive.”
The weaknesses of this method is explained in line 579-587
“Even though this monitoring technique is capable of identifying the stepper motor problems, however, the method is limited on the electrical related problems. The mechanical related CRDM problems such as the faults in magnetic damper, the gear box, sprocket wheel, worm-gear reducer might not be detected through the voltage and stator current measured signals easily.”
Please return to Atom Indonesia Editorial Office via e-mail: [email protected] and Faximile: 021-7560895.
This original sheet should be returned to:
Tata Usaha Atom Indonesia, PPIKSN-BATAN, Gedung 71, Lantai 1, Kawasan Puspiptek Serpong, Tangerang, Indonesia 15310
Author Signature(s) Date 28 August 2015
Syaiful Bakhri
ATOM INDONESIA JOURNAL 2
ndAuthor's Responses
Article : #406
Name of All Authors : Syaiful Bakhri, Nesimi ertugrul
Article Title : An Online Non-Invasive Condition Monitoring Method for Stepping Motor CRDM in HTGR
E-mail : [email protected]
Line # Referee’s Comments Author's Responses
The manuscript must be using the current literatures (80% of the references should be published within 5 years [2010-2015] and from the primary reference sources/journals).
