Protection System of the DTT Toroidal Magnets FAQ

Referring to the general layout, is it possible to install either the complete Discharge Resistors or part of them, on the building roof?

Yes your proposal can be accepted, but it will be deep discussed and definitely agreed during DDP.

Test to verify the electrodynamic resistance of the PB (§7.2.3-3):

Remembering that the current in the PyroBreaker is unidirectional, we propose to perform this test with current pulses of 85 kA, length 100 ms, repeated 5 times; is this acceptable?

Yes your proposal can be accepted, but it will be deep discussed and definitely agreed during DDP.

Dummy Load

we understand that the Dummy Load is an inductor rated 48 mH; could you please confirm?

could you please confirm that the Dummy Load is provided by DTT, and will be made available in the IS factory for the execution of the tests?

could you please indicate the resistance of the inductor and give us an idea about the terminals/connections?

could you please indicate what is necessary for the cooling of the Dummy Load?

could you please give indications regarding dimensions and weight of the Dummy Load?

1) Dummy load is part of another procurement. Its preliminary characteristics are 2mH at a current, between 10 and 15 kA and air/water cooling.
2) It will not be made available for factory test (as well as the TFPS), but for on-site acceptance tests.
3) At the moment the TFPS contract is not still awarded, thus these data are not available.
4) Please see above.
5) Please see above.

§ 7.2.1 - 6) Test to verify the electric wear of the sacrificial contacts of the BPS

Which are the ratings of the power supply to perform this test?

In case this test is not feasible in the factory, is it possible to do it as a test on the site, using the TF power supply and the Dummy Load?

Yes, this could be acceptable, but how to perform the test shall be deep discussed in its implications and definitely agreed during DDP. Moreover any issue caused by malfunction of the sacrificial contacts (as well as not correct design of them or the damage of other parts) is under responsibility of IS and their replacement is at its expense.

§ 7.2.3 – 4) Test to verify the current interruption capability of the PB:
"The Pyrobreaker shall be to interrupt the dc current and then to commutate it in a resistance
connected in parallel,..."

As an alternative to DC current, is it possible to use a quarter of a period of an AC current at mains frequency, controlling the opening on the peak of the sinusoid?
Otherwise: what minimum characteristics must the DC power supply have for this test? (in terms of voltage -> power)

This could be acceptable, but only during the DDP and only after defining and discussing the test conditions and its implications.

"Mock-up

In your previous answer:
""Both the following options are possible:
1) The mock-up (prototype) can be one the three final FDUs with some predispositions/adaptations/reconfigurations that allow it to be configured as a mock-up.
2) The components of the mock-up can be resused for one of the three final FDUs"".
Now we see three possibilities:
a) Mock-up is one independent unit (without PB, with different DR…) -> total: 3 + 1 units
b) components of the Mock-Up will be reused in the 3 FDU units
c) Mock-up is one of the three FDUs with some predispositions -> total: 2 + 1 units.
For the purposes of the technical score in the tender, are the three possibilities equivalent?
If so, we will aim to reduce the tender price; if not, how the different possibilities will be technically evaluated?"

All the 3 proposed options are acceptable. Obviously, whether an ecomomic operator in its technical offer delivers 3 FDU plus a mock-up, it will have a higher score during technical evaluation.

DUTY CYCLE

In the new Technical Specification (Rev 1.2):
• the Maximum time between intervention and restart of operation is now 120 min (Table 33, Table 34)
• the Duty Cycle remains 60 min, both for the entire FDU, and for the Dumping Resistor (Table 1, Table 33, Table 34)

We think that this is a typo: the Duty Cycle is now 120 min; could you please confirm, or comment?

Yes, the duty cycle of 60 min is related to the DTT operations. It is not significant for the TF FDU, since TF magnets are continuously operating. Only in case of FDU fast discharge, consider a time of 120 min after a fast discharge for thermal design.

§ 7.2.4-3 Test to verify the electro-dynamic resistance of the DR:

"A short‐time current of 47 kA shall be applied to one module of the Dump Resistor"

In your previous answer you write:
"However, the test shall be carried out with a current of 47 kA on a complete DR module representative of components connected in series and in parallel."

In case the DR is made with N1 x N2 assemblies (N1 in series and N2 in parallel), the complete DR module you mean for this test is made with N2 assemblies in parallel; correct?
In this case we are wondering how if it is practically feasible (which are the power ratings of the generator for this test?)
We propose to perform the test on a single assembly, with a short‐time current of 47 / N2 x 1.2 kA
(where "1.2" takes into account possible unbalances)

Your proposal can be accepted. Nevertheless whether another economic operator in its technical offer states to perform the “Test to verify the electro-dynamic resistance of the DR” on a complete DR module, during technical evaluation it will have a higher score.

Current sensors - SCB

Ref.: § 5.24.2.2. measurements from SCB, and Table 18:

1) Is it really necessary to have the single measures of the current in each SCB branch, also considering the limited conduction time of the SCB?
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2) About current sensors for SCB, we see two possible alternative implementations; let us call "N" the number of parallel branches of the SCB:
a) A single high current DCCT rated 45 kA to measure the total current, with the addition of N sensors - one on each SCB branch - that give a signal when current variation is detected in the branch (in order to timely detect and manage if one branch fails)
b) N sensors (DCCTs), one per branch, with full scale rating around 45 kA / N x 1.2 (instead of 45 kA); the SCB total current will be the sum of the N DCCT outputs.

Are both solutions a) and b) acceptable?

1) Yes, because these data are useful for diagnostic and control purposes.
2) Both solutions can be acceptable. Nevertheless you consider that the level of redundancy is an evaluation feature of the technical offer, therefore a higher redundancy level will be evaluated with a higher score.

Could you please provide a "track-change" version of the Technical Specification, showing the modifications with respect to the first version?
Alternatively, could you please provide the detailed list of modifications?

I cannot provide a file in track version. Nevertheless I can provide list of changes as follows:
Table 1 (footnote 1);
Table 15, 18, 21, 24, (bandwidth);
5.24.11. Layout and installation requirements;
Table 33 and 34 (Maximum time between intervention (with initial room air temperature of 25°C) and restart of operation);
Par. 7.2.2. Static Circuit Breaker (bullet 1, 2, 3, 4);
Par. 7.2.4. Dump Resistor (bullet 3);
Par. 7.2.5. Hybrid Circuit Breaker;
Par. 7.2.8. Whole Fast Discharge Unit (bullet 3);

Referring to Document ID: PSSSPT-903_1_1, paragraphs 7.2.2 - 7.2.5 – 7.2.8 and 7.3.2 , please inform us the possibility to perform such tests at site (Frascati).

Tests referred to paragraphs 7.2 and 7.3 (and their Subparagraphs) are related to type and routine factory tests. Whether in your laboratories these tests can not be performed, you need to perform them in an external laboratory. For Tender purposes, these tests cannot be performed in the ENEA Frascati laboratories.

Referring to Document ID: PSSSPT-903_1_1 , paragraph 5.24.3.1, “…The increase of the resistance of a single module due to adiabatic heating corresponding to the maximum energy shall be less than 15% of the nominal value (TBC in the DDP)…” please inform us if a higher increase of the resistance is acceptable (for example 20÷25%).

Yes, I can confirm that an increase of the resistance of a single module in a range 20-25% is acceptable.