source: Test Procedure and Acceptance Criteria for the 600 A Circuits, MP3 Procedure, <ahref="https://edms.cern.ch/document/874716">https://edms.cern.ch/document/874716</a>
%% Cell type:markdown id: tags:
# Analysis Assumptions
- We consider standard analysis scenarios, i.e., all signals can be queried. If a signal is missing, an analysis can raise a warning and continue or an error and abort the analysis.
- It is recommended to execute each cell one after another. However, since the signals are queried prior to analysis, any order of execution is allowed. In case an analysis cell is aborted, the following ones may not be executed (e.g. I\_MEAS not present).
# Plot Convention
- Scales are labeled with signal name followed by a comma and a unit in square brackets, e.g., I_MEAS, [A].
- If a reference signal is present, it is represented with a dashed line.
- If the main current is present, its axis is on the left. Remaining signals are attached to the axis on the right. The legend of these signals is located on the lower left and upper right, respectively.
- The grid comes from the left axis.
- The title contains timestamp, circuit name, and signal name allowing to re-access the signal.
- The plots assigned to the left scale have colors: blue (C0) and orange (C1). Plots presented on the right have colors red (C2) and green (C3).
- Each plot has an individual time-synchronization mentioned explicitly in the description.
- If an axis has a single signal, then the color of the label matches the signal's color. Otherwise, the label color is black.
In order to perform the analysis of a FPA in an 600A circuit with/without EE please:
1. Select circuit family (e.g., RCS)
2. Choose start and end time
3. Choose analysis mode (Automatic by default)
Once these inputs are provided, click 'Find FGC PM' button entries'. This will trigger a search of the PM database in order to provide a list of timestamps of FGC events associated with the selected circuit name for the provided period of time. Select one timestamp from the 'FGC PM Entries' list to be processed by the following cells.
**Note that 24 hours is the maximum duration of a single PM query for an event. To avoid delays in querying events, please restrict your query duration as much as possible.**
The analysis for MP3 consists of checking the existence of PM file and of consistency of the PM timestamps (PC, QPS, EE if applicable). The criterion of passing this test described in detail in 600APIC2.
In short the following criteria should be checked:
- 2 PM DQAMGNA (A+B) files and 1 PM EE file should be generated for 600 A circuits with EE
- Difference between QPS board A and B timestamp = 1 ms
- PC timestamp is QPS timestamp +/- 20 ms
- EE timestamp is +/-20 ms from the QPS timestamp
If one or more of these conditions are not fulfilled, then an in-depth analysis has to be performed by the QPS team.
The quench voltage U_RES is calculated according to the following formula:
\begin{equation}
U_{\text{RES}} = U_{\text{DIFF}} + L d/dt (I+U_{\text{DIFF}}/R).
\end{equation}
Note that I_DCCT is the QPS signal name, even though the current is actually measured not with a DCCT, but with a LEM detector, hence the poorer quality w.r.t. to the FGC I_A/B/MEAS signals that are measured with a DCCT.
It can be seen from the sign convention in the figure below that a resistive voltage always has opposite sign to the measured current.
As U_DIFF contributes directly to U_RES, the resolution of U_RES is, at least partially, limited by that of U_DIFF. Moreover, U_RES is affected by the noisy time derivative of the current signal.
The QPS signals that are communicated to the post-mortem system have only 12 bit resolution.
%% Cell type:markdown id: tags:
## 6.1. Resistive Voltage
*ANALYSIS*:
- Check if the U_RES signal before a quench is increasing for at least one board, which would indicate a QPS trip
- Calculate the initial voltage slope of U_RES signal. The slope is calculated as a ratio of the voltage change from 50 to 200 mV and the corresponding time change.
*GRAPHS*:
First plot (U_RES and I_MEAS prior to a quench)
- t = 0 s corresponds to the FGC timestamp
Second plot (U_RES and the initial slope of U_RES)
- Check the integrity of all four signals (U_DIFF, I_DCCT, I_DIDT and U_RES). If one of the signals (especially U_DIFF or I_DCCT) stays at zero or shows wrong values the cabling of this quench detector could have issues. Compare U_DIFF (measured signal) to U_REF (signal compensated for inductive voltage).
analysis.results_table['FPA Reason']=get_expert_decision('Reason for FPA: ',['QPS trip','Converter trip','EE spurious opening','Spurious heater firing','Busbar quench','Magnet quench','HTS current lead quench','RES current lead overvoltage','No quench','Unknown'])
analysis.results_table['Type of Quench']=get_expert_decision('Type of Quench: ',['Training','Heater-provoked','Beam-induced','GHe propagation','QPS crate reset','Single Event Upset','Short-to-ground','EM disturbance','No quench','Unknown'])
analysis.results_table['QDS trigger origin']=get_expert_decision('QDS trigger origin: ',['QPS','HTS current lead','RES current lead','Busbar','No quench'])
<h1><center>Analysis of a PLI2.e3 HWC Test in an IPQ Circuit</center></h1>
The Individually Powered Quadrupole magnets (IPQs) in the LHC are located on both sides of the Interaction Regions (IR), in the matching sector and in the dispersion suppressor. The IPQ circuits RQ4 to RQ7 are part of the matching sector, and the IPQ circuits RQ8 to RQ10 are part of the dispersion suppressor. The magnets Q4 to Q6 are operated at
4.5 K, whereas the magnets Q7 to Q10 are operated at 1.9 K.
The MQM quadrupole consists of two individually powered apertures assembled in a common yoke structure.
The MQY wide-aperture quadrupole consists of two individually powered apertures assembled in a common yoke structure.
### PLI2.E3 - SPLICE MAPPING AND UNBALANCED SLOW POWER ABORT
For the HWC 2014, this test has been modified to include splice mapping. By increasing the current level from I\_INTERM\_1 to I\_INTERM\_2, the difference in maximum current between this test and next test at I\_PNO is reduced. In addition a plateau at I\_INJECTION is added to serve the splice mapping.
The aim of this test is to verify the response of both power converters in case of Slow Power Abort with unbalanced currents and to perform splice mapping.
<center>Current during PLI2.E3 for tests starting from 2014 HWC. The actual values of current may deviate from the values shown above.</center>
Offline analyses are listed below:
|Responsible|Type of Analysis|Criteria|
|-----------|----------------|--------|
|PC|Verify acceleration and ramp rate of the PCs||
|PC|PC voltage and current||
|MP3|Check if QPS tripped (it is not expected).||
| |Check if PM file was created (it is not expected).||
| |Calculate splice resistances (**not possible due to limited logging resolution**)||
| |Check DFB regulation|T_top_HTS = 50 +/- 4 K|
| ||T_top_Cu = temperature at 0 A current +/- 10 K|
source: Test Procedure for the Individually Powered 4-6 kA Quadrupole-Circuits in the LHC Insertions, MP3 Procedure, <ahref="https://edms.cern.ch/document/874884">https://edms.cern.ch/document/874884</a> (Please follow this link for the latest version)
%% Cell type:markdown id: tags:
# Analysis Assumptions
- We consider standard analysis scenarios, i.e., all signals can be queried. If a signal is missing, an analysis can raise a warning and continue or an error and abort the analysis.
- It is recommended to execute each cell one after another. However, since the signals are queried prior to analysis, any order of execution is allowed. In case an analysis cell is aborted, the following ones may not be executed (e.g. I\_MEAS not present).
# Plot Convention
- Scales are labeled with signal name followed by a comma and a unit in square brackets, e.g., I_MEAS, [A].
- If a reference signal is present, it is represented with a dashed line.
- If the main current is present, its axis is on the left. Remaining signals are attached to the axis on the right. The legend of these signals is located on the lower left and upper right, respectively.
- The grid comes from the left axis.
- The title contains timestamp, circuit name, and signal name allowing to re-access the signal.
- The plots assigned to the left scale have colors: blue (C0) and orange (C1). Plots presented on the right have colors red (C2) and green (C3).
- Each plot has an individual time-synchronization mentioned explicitly in the description.
- If an axis has a single signal, then the color of the label matches the signal's color. Otherwise, the label color is black.
The signal names used for quench detection are shown in the figure below (*please run a cell below to display a QPS circuit schematic corresponding to the circuit name under analysis*).
- Check if the temperatures TT893 at the top of the copper part of the four current leads, is over dew point, but not overheated: 280 K < TT893 < 320 K, even without current
- Check if the temperatures TT891A at the top of the HTS part of the four current leads, is regulated around 50 K: 46 K < TT891A < 54 K, even without current
The current in the circuit is increased to I_INJECTION and shortly maintained constant. A quench simulation from one current lead is performed provoking a discharge of the energy through the EE system. The aim of the test is to check at a low current level the performance of the QPS and EE systems.
From 2010 on, a time delay is implemented between the switch opening and the FPA signal received (300 ms at the odd point, 600 ms at the even point).
The required analysis and signatures are listed below.
|Responsible|Type of analysis|Criterion|
|-----------|----------------|---------|
|PC|PC voltage check|PC voltage ~ -1.5 V ± 0.5 V, 1 s after the EE activation. The current decay time constant should be within 20% of Decay_Time_const. Smooth exponential waveform on the PC voltage and current during the whole decay|
|PC|Earth Current Analysis|The maximum earth current <50 mA during EE activation disregarding the peak at the opening of the EE system.|
|EE|Energy discharge|Maximum voltage on EE resistance ($R*I$±10%) and maximum temperature of the EE resistance (±10% from theoretical value)|
|EE|Energy discharge|Time delay on switch opening (300±50ms at odd point and 600±50ms at even point)|
source: Powering Procedure and Acceptance Criteria for the 13 kA Dipole Circuits, MP3 Procedure, <ahref="https://edms.cern.ch/document/874713">https://edms.cern.ch/document/874713</a> (Please follow this link for the latest version)
%% Cell type:markdown id: tags:
# Analysis Assumptions
- We consider standard analysis scenarios, i.e., all signals can be queried. If a signal is missing, an analysis can raise a warning and continue or an error and abort the analysis.
- It is recommended to execute each cell one after another. However, since the signals are queried prior to analysis, any order of execution is allowed. In case an analysis cell is aborted, the following ones may not be executed (e.g. I\_MEAS not present).
# Plot Convention
- Scales are labeled with signal name followed by a comma and a unit in square brackets, e.g., I_MEAS, [A].
- If a reference signal is present, it is represented with a dashed line.
- If the main current is present, its axis is on the left. Remaining signals are attached to the axis on the right. The legend of these signals is located on the lower left and upper right, respectively.
- The grid comes from the left axis.
- The title contains timestamp, circuit name, and signal name allowing to re-access the signal.
- The plots assigned to the left scale have colors: blue (C0) and orange (C1). Plots presented on the right have colors red (C2) and green (C3).
- Each plot has an individual time-synchronization mentioned explicitly in the description.
- If an axis has a single signal, then the color of the label matches the signal's color. Otherwise, the label color is black.
## 4.2. Analysis of the Power Converter Main Current
This analysis module displays the main current of the power converter (I_MEAS) compared to the one obtained from the reference FPA (HWC PNO.b2 test with opening of EE systems and without magnet quench).
*ANALYSIS*:
- The evolution of the characteristic time $\tau$ of an exponential decay $f(t)$ is obtained as
Naturally, this formula only applies to exponential decayed characterised by a time constant. Nonetheless, for pseudo-exponential decays, this formula gives a notion of the change of the characteristic time $\tilde{\tau}$. For a circuit we compute the time-varying characteristic time as
- Check if the characteristic time of pseudo-exponential decay of I_MEAS from t=1 to 120 s is 90 s< Tau <110 s
*PLOT*:
- The main power converter current (analyzed and reference) on the left axis, I_MEAS
- The characteristic time calculated for the main current (reference and actual) on the right axis, -I_MEAS/dI_MEAS_dt
The actual characteristic time contains steps, which indicate a quenching magnet (decrease of circuit inductance); note that for the reference one the steps are not present. Timing of PIC abort, FGC timestamp, and the maximum current are reported next to the graph.
- t = 0 s corresponds to the respective (analyzed and reference) FGC timestamps.
## 4.3. Analysis of the Power Converter Main Current Smoothness
*ANALYSIS*:
- The current smoothness is evaluated on the basis of its second derivative. The derivative is calculated as a rolling division of current and time differences. The rolling window is fixed and equal to 10 points; with the sampling time equal to 0.1 s the time difference is equal to $dt=1 s$.
\begin{equation}
\frac{d i(t)}{dt} = \frac{i(t+dt)-i(t)}{dt}
\end{equation}
To obtain the second derivative of the current decay, the formula above is applied twice to the current profile from PM after the second EE opening (for t > 1 s).
*CRITERIA*
- Check if the second derivative of the current decay of I_MEAS from t = 1 s is -10 A/s^2< dI_MEAS/dt^2 < 10 A/s^2
*PLOT*:
- The second derivative of the main power converter current on the left axis, dI_MEAS/dt^2
- Green bar denotes the acceptance threshold for the second derivative of the main power converter current
- The main power converter current on the right axis, I_MEAS
%% Cell type:code id: tags:
``` python
title = create_hwc_plot_title_with_circuit_name(circuit_name=circuit_name, hwc_test=hwc_test, t_start=t_start, t_end=t_end, signal='I_MEAS smoothness')
source: Powering Procedure and Acceptance Criteria for the 13 kA Dipole Circuits, MP3 Procedure, <ahref="https://edms.cern.ch/document/874713">https://edms.cern.ch/document/874713</a>
%% Cell type:markdown id: tags:
# Analysis Assumptions
- We consider standard analysis scenarios, i.e., all signals can be queried. If a signal is missing, an analysis can raise a warning and continue or an error and abort the analysis.
- It is recommended to execute each cell one after another. However, since the signals are queried prior to analysis, any order of execution is allowed. In case an analysis cell is aborted, the following ones may not be executed (e.g. I\_MEAS not present).
# Plot Convention
- Scales are labeled with signal name followed by a comma and a unit in square brackets, e.g., I_MEAS, [A].
- If a reference signal is present, it is represented with a dashed line.
- If the main current is present, its axis is on the left. Remaining signals are attached to the axis on the right. The legend of these signals is located on the lower left and upper right, respectively.
- The grid comes from the left axis.
- The title contains timestamp, circuit name, and signal name allowing to re-access the signal.
- The plots assigned to the left scale have colors: blue (C0) and orange (C1). Plots presented on the right have colors red (C2) and green (C3).
- Each plot has an individual time-synchronization mentioned explicitly in the description.
- If an axis has a single signal, then the color of the label matches the signal's color. Otherwise, the label color is black.
Table below provides timestamps ordered achronologically and represents the sequence of events that occurred in the analyzed circuit. Only the first PIC timestamp is reported. Note that for iQPS and nQPS only the first timestamp is reported. Tables with all iQPS and NQPS timestamps are presented in the section dedicated to magnet and quench protection analysis. The table also contains time difference in milliseconds from the first event and from the FGC event.
In short, the following criteria should be kept:
- The PC timestamp (51_self) is QPS time stamp +/-20 ms.
- Time stamp difference between FGC and EE at an odd (RR or UJ) point: 290±50 ms
After YETS 2017/8 the EE timestamp odd has been reduced and should now be 100+-50 ms after the FGC time stamp
- Time stamp difference between FGC and EE at an even (UA) point: 600±50 ms
Table below contains reference timestamps of signals used for comparison to the analyzed FPA. The reference comes as the last PNO.b2 HWC test with activation of EE systems and no magnets quenching.
- Show warning if the two PIC timestamps differ by more than a 1 ms.
%% Cell type:code id: tags:
``` python
rb_analysis.analyze_pic(timestamp_pic)
```
%% Cell type:markdown id: tags:
# 6. Power Converter
## 6.1. Analysis of the Power Converter Main Current
This analysis module displays the main current of the power converter (I_MEAS) compared to the one obtained from the reference FPA (HWC PNO.b2 test with opening of EE systems and without magnet quench).
*ANALYSIS*:
- The evolution of the characteristic time $\tau$ of an exponential decay $f(t)$ is obtained as
Naturally, this formula only applies to exponential decayed characterised by a time constant. Nonetheless, for pseudo-exponential decays, this formula gives a notion of the change of the characteristic time $\tilde{\tau}$. For a circuit we compute the time-varying characteristic time as
- Characteristic time of pseudo-exponential decay of I_MEAS from t=1 to 120 s: 90 s< Tau <110 s
*PLOT*:
- The main power converter current (analyzed and reference) on the left axis, I_MEAS
- The characteristic time calculated for the main current (reference and actual) on the right axis, -I_MEAS/dI_MEAS_dt
The actual characteristic time contains steps, which indicate a quenching magnet (decrease of circuit inductance); note that for the reference one the steps are not present. Timing of PIC abort, FGC timestamp, and the maximum current are reported next to the graph.
- t = 0 s corresponds to the respective (analyzed and reference) FGC timestamps.
|DQAMCNMB_PMSTD |iQPS, DQQDL |100 mV |10 ms discrimination |U_QS0 |Old QPS. Detection of quench in one aperture based upon voltage difference between both apertures in same magnet U_QS0 >10 ms above threshold, otherwise discriminator is reset|
|DQAMCNMB_PMHSU |iQPS, nQPS |-|-|-|Firing of quench heaters by quench protection. Generation of PM buffers sometimes happens even if there is no heater firing.|
|DQAMGNSRB (slow sampling rate), DQAMGNSRB_PMREL (fast sampling rate) |nQPS, DQQDS |500 mV * |>20 ms moving average +1 ms discrimination |U_DIODE |New QPS. Detection of quench in both apertures based upon comparing voltage across the magnet (bypass diode) from 3 magnets in same half-cell and one reference from adjacent half-cell. 50Hz notch moving average filter (20ms worst case). The signals in the 2 classes are identical, only the sampling rate differs. The data with the slow sampling rate is no longer generated as they can be found in the logging database. The recording of data is usually triggered during a FPA, depending on current in circuit, and always when a symmetric quench occurs. The PM buffers are only sent if the DQAMGNS crate trips (what ever the reason).|
|DQAMGNSRB |nQPS, DQQBS| 4 mV | >10 s moving average | U_RES |New QPS. Busbar protection. The signal is not compensated for inductive voltage during ramp.|
|DQAMGNDRB_EVEN, DQAMGNDRB_ODD |iQPS, DQQDC |1 mV, 100 mV |1 s |U_HTS, U_RES |Old QPS. Leads protection. U_HTS is for the high temperature superconducting leads, and U_RES is for the room temperature leads.|
|DQAMGNDRB_EVEN, DQAMGNDRB_ODD |iQPS, DQQDB |+200 V | -50 V | U_BB1, U_BB2 |Old QPS. U_BB1 is the total voltage across the sector. U_BB2 is the voltage across the energy extraction (EE)|
|DQAMSNRB |-|-|-|-|Opening of energy extraction (EE) switches during fast power abort (FPA). 2 EE switches per sector. One for "even" points (EE2). One for "odd" points (EE1).|
*: It was 800 mV before LS1. After LS1 we changed it to 300 or 400 mV. During the training after LS1 we increased it to 500 mV.
%% Cell type:markdown id: tags:
## 8.1. Plot of Voltage Across All Magnets (U_DIODE_RB)
*PLOT*:
t = 0 s corresponds to the PM timestamp of the FGC
First plot (global)
- the power converter current on the left axis, I_MEAS
- diode voltage on the right axis, U_DIODE_RB
Second plot (zoom)
- the power converter current on the left axis, I_MEAS
- calculates the current at which a quench occured by finding the timestamp of the current dataframe (i_meas_df) closest to the quench time and the curresponding value of current - I_MEAS_quench
- determines the type of the QPS board that generated the PM entry (a board could fail to write to PM) - i_qps_board_type
- compute the time difference (in seconds) from the first quench - dt_quench
## 8.3. Analysis of Quench Detection Voltage and Logic Signals for Quenched Magnets
%% Cell type:markdown id: tags:
*ANALYSIS*:
- finds the first timestamp, t_st_magnet_ok, for which the ST_MAGNET_OK signal is False indicating that the quench detection signal U_QS0 is outside of the +/- 100 mV threshold.
- for t > t_st_magnet_ok, finds the first timestamp, t_st_nqd0 for which the ST_NQD0 signal is Fals indicating that the U_QS0 signal is outside of the +/- 100 mV threshold for more than the 10 ms discrimination time. This signifies quench detection and results in triggering quench heaters.
- finds U_QS0 value at the moment of quench detection, u_ST_NQD0 = U_QS0(t=t_st_nqd0)
- if the minimum value of the absolute value of U_QS0 is above greater than 100 ms, then find the start time of a quench, t_start_quench, as a moment at which U_QS0 value is 10 mV greater than its initial value. Otherwise, the start time of a quench is set to 0 s.
- finds U_QS0 value, u_start_quench, at the moment of quench start as u_start_quench = U_QS0(t=t_start_quench)
- the slope of the quench detection signals is calculated as du_dt = (u_ST_NQD0 - u_start_quench) / (t_st_nqd0 - t_start_quench)
- the quench detection signal polarity is taken as the sign of its slope
- the delay of the quench heaters triggering, t_delay_qh_trigger, is assumed to be the negative value of t_st_magnet_ok, t_delay_qh_trigger = -t_st_magnet_ok
Determine source of QH trigger for nQPS signals in PM:
- calculates nQPS differences for the symmetric quench detection
- selects only the differences that involve the quenched magnet and exclude already quenched magnets in the cell
- for t in [-0.2 s, t_st_magnet_ok] take the maximum value of voltage difference
- if the maximum is above 1V (considering sun glasses active from t = 0 s) and the time of maximum is less than t_st_magnet_ok, than the QH system was triggered by nQPS, otherwise iQPS
- it is assumed that the first training quench was detected by iQPS
*PLOT*:
t = 0 s corresponds to the PM timestamp of the QDS
Upper left (iQPS analog signals)
- the quench detection voltage on the left axis, U_QS0
- voltage across the first and the second aperture on the right axis, respectively, U_1 and U_2
- the green box denotes an envelope of the +/- 100 mV quench detection threshold
- the orange box denotes an envelope of the rise of the quench signal from its start until reaching the threshold
Lower left (iQPS digital signals)
- the quench detection voltage on the left axis, U_QS0
- digital quench detection signals, ST_MAGNET_OK, ST_NQD0
- the green box denotes an envelope of the +/- 100 mV quench detection threshold
- the orange box denotes an envelope of the rise of the quench signal from its start until reaching the threshold
Upper right (nQPS analog signals)
For PM signals (global view)
- the diode voltages used by the nQPS crate for quench detection on the left axis, U_DIODE_RB and U_REF_N1
For NXCALS signals (global view)
- the diode voltages used by the nQPS crate for quench detection on the left axis, U_DIODE_RB and U_REF_N1
Lower right (nQPS analog signals)
For PM signals (difference view)
- the differences of diode voltages (containing the quenched magnet; in case the signals are missing, the plot is not displayed) used by the nQPS crate for quench detection on the left axis, U (Calculated diode differences)
- the green box denotes an envelope of 1 V quench detection threshold (assuming active 'sun glasses') before the iQPS quench detection. If the nQPS difference goes outside of the envelope, it means that the quench was detected by nQPS.
For NXCALS signals (zoomed view)
- the diode voltages used by the nQPS crate for quench detection on the left axis, U_DIODE_RB and U_REF_N1
- calculates diode lead resistance from voltage (board A and B) and current
*CRITERIA*
- if the maximum resistance is above 50 uOhm, then raise a warning
- if the maximum resistance is above 150 uOhm, then raise an alarm
*PLOT*:
Upper PM (Input view)
- the main power converter current on the left axis, IAB.I_A
- quenched magnet voltage from two boards, U_DIODE_A, U_DIODE_B. The difference between both signals is the diode lead voltage.
- reference nQPS board voltage on the right axis, U_REF
- diplayed on the left only if a quench occured no later than 2 seconds after the FGC PM timestamp
- t = 0 s corresponds to the PM timestamp of the QPS
Lower PM (Output view)
- the main power converter current on the left axis, IAB.I_A
- the calculated diode lead resistance on the right axis, R_DIODE_LEADS
- diplayed on the left only if a quench occured no later than 2 seconds after the FGC PM timestamp
- t = 0 s corresponds to the PM timestamp of the QPS
Upper CALS (Input view)
- the main power converter current on the left axis, I_MEAS
- quenched magnet voltage from two boards is saved as a single signal, U_DIODE_RB. The two signals are stored by means of value toggling between board A and board B. The difference between both sub-signals is the diode lead voltage.
- t = 0 s corresponds to the PM timestamp of the FGC
Lower CALS (Output view)
- the main power converter current on the left axis, I_MEAS
- the calculated diode lead resistance on the right axis, R_DIODE_LEADS
- t = 0 s corresponds to the PM timestamp of the FGC
