ECR Title: Addition of DC Power Breaker Switch Boxes (D1400007-v1) in-line with HEPI Pier Pods (D080520), and TCS ISS Chassis (D1300649).	DCC No: E1400052-v2
Date: 5 February, 2014
Requester: Ben Abbott	Impacted Subsystem(s): ISI, TCS
Description of Proposed Change(s): The HEPI Pier Pods, and TCS ISS Chassis both have small power switches that don’t have any circuit breaker functionality. Due to a recent chassis failure, it has been deemed reasonable to include some circuit breakers in their power lines. The proposed breaker would live in the rack from whence the power is delivered, and would protect everything downstream.
Reason for Change(s): A recent failure has brought to our attention the danger of un-limited power supplies. Any instance of a chassis that is fed from a supply with no circuit protection needs to be mitigated.
Estimated Cost: $4500 for materials/supplies plus $830 in assembly charges from an outside vendor for 40 units. Total estimated cost = $5.5K. (6/40ths TCS, and 34/40ths SEI)
Schedule Impact Estimate: Minimal
Nature of Change (check all that apply): Safety Correct Hardware Correct Documentation	Improve Hardware Improve/Clarify Documentation Change Interface Change Requirement
Importance: Desirable for ease of use, maintenance, safety Desirable for improved performance, reliability Essential for performance, reliability Essential for function Essential for safety	Urgency: No urgency Desirable by date/event: _before final acceptance Essential by date/event: ____________ Immediately (ASAP)
Impacted Hardware (select all that apply): Repair/Modify. List part & SNs: ______________________ Scrap & Replace. List part & SNs:_____________________ Installed units? List IFO, part & SNs: _________________ Future units to be built	Impacted Documentation (list all dwgs, design reports, test reports, specifications, etc.): SEI System Schematic diagrams D0901301-v10, D1101584-v6, D1101576-v8, D1000298-v6, and TCS Block Diagrams, E1100892-v23 and E1100891-v11.
Disposition of the proposed change(s): The disposition of this proposed engineering change request is to be completed by Systems Engineering and indicated in the “Notes and Changes” metadata field in the DCC entry for this ECR. The typical dispositions are as follows: Additional Information Required: in which case the additional information requested is defined. The ECR requester then re-submits the ECR with the new information using the same DCC number for the ECR but with the next version number. Rejected: in which case the reason(s) for the rejection are to be given Approved Approved with Caveat(s): in which case the caveat(s) are listed TRB: the ECR is referred to an ad-hoc Technical Review Board for further evaluation and recommendation. It is the System Engineer’s (or designee’s) responsibility to organize the TRB. The System Engineer (or designee) then makes a technical decision based on the TRB’s recommendation. Links to the TRB’s documentation (charge, memos, final report, etc.) are to be added to the “Related Documents” field for this ECR. CCB: a change request for approval of additional funds or schedule impact is to be submitted to the Configuration Control Board. Links to the CCB’s documentation (CR, etc.) are to be added to the “Related Documents” field for this ECR. Concurrence by Project Management: Acknowledgement/acceptance/approval of the disposition is to be indicated by the electronic “signature” feature in the DCC entry for this ECR, by one the following personnel: Systems Scientist Systems Engineer Deputy Systems Engineer