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Re: Metrolink, Coaster, Amtrak survey says
Author: SP5103
Date: 06-22-2014 - 10:06
Checked with a friend that works for MPI and he said the only 575v HEP he was aware of was GO Transit and VIA. I am guessing 575v this was the result of either a rogue consultant or engineer or for the real need to get more power through the same size HEP cables.
The HEP specs I have seen specified two runs (3 cables, one for each phase, X 2) down each side of the car, plus wire for the safety/continuity circuits. These 12 cables are 4/0, but not the commercial stuff you find at Home Depot. This is actually 550/24 DLO (550 strands of #24 fine wire) which is flexible (also soft copper instead of hard drawn) and high capacity. I use Exane which is a high quality DLO rated at 510 amps at 125 degrees centigrade (not confined in conduit) which is available in 2000v insulation. This cable is typically used in full size locomotives to connect to the batteries, but can be found as traction motor cable on small locomotives.
By increasing from 480v to 575v you would gain almost 20% capacity at the same amperage. Assuming a conservative rating of 400 amps for each of the four runs, a 480v system would be capable of 768kw but a 575v system would be 920kw. Most commercial motors and control systems are typically insulated for 600v anyway, but that means all the motors and transformers have to be specially wound for 575v instead of 480v. I've probably got this wrong because I usually deal with DC and I AC components often have higher ratings than DC because of the alternating current.
I know there is at least two different "standards" of HEP arrangements. One system ties all four runs together as a common buss(?). If I remember right (without digging for three days to find the info), VIA uses a split arrangement where each side of the car is a separate circuit and the car equipment is divided equally between them. This wouldn't be an issue in normal operation, but if part of the HEP system fails due to damage or being able to maintain the continuity of the safety circuit, it must be "short looped" to eliminate the damaged section. I think the VIA system is designed to provide greater redundancy and capacity if the event of an HEP issue.
The HEP specs I have seen specified two runs (3 cables, one for each phase, X 2) down each side of the car, plus wire for the safety/continuity circuits. These 12 cables are 4/0, but not the commercial stuff you find at Home Depot. This is actually 550/24 DLO (550 strands of #24 fine wire) which is flexible (also soft copper instead of hard drawn) and high capacity. I use Exane which is a high quality DLO rated at 510 amps at 125 degrees centigrade (not confined in conduit) which is available in 2000v insulation. This cable is typically used in full size locomotives to connect to the batteries, but can be found as traction motor cable on small locomotives.
By increasing from 480v to 575v you would gain almost 20% capacity at the same amperage. Assuming a conservative rating of 400 amps for each of the four runs, a 480v system would be capable of 768kw but a 575v system would be 920kw. Most commercial motors and control systems are typically insulated for 600v anyway, but that means all the motors and transformers have to be specially wound for 575v instead of 480v. I've probably got this wrong because I usually deal with DC and I AC components often have higher ratings than DC because of the alternating current.
I know there is at least two different "standards" of HEP arrangements. One system ties all four runs together as a common buss(?). If I remember right (without digging for three days to find the info), VIA uses a split arrangement where each side of the car is a separate circuit and the car equipment is divided equally between them. This wouldn't be an issue in normal operation, but if part of the HEP system fails due to damage or being able to maintain the continuity of the safety circuit, it must be "short looped" to eliminate the damaged section. I think the VIA system is designed to provide greater redundancy and capacity if the event of an HEP issue.
