Power relay datasheet GU-SS-124DFS clarification/confusion - Page 1
Forum section: electronics / beginners

author: retiredcaps
author_rank: Super Contributor
timestamp: November 29, 2015, 06:50:21 am
content: == short version ==I need help interpreting the markings on this GU-SS-124DFS relay wrt to its datasheet.== long version ==My friend, in Canada (120V AC), has a bad relay in a vending (pop) machine. A picture of it is included.According the Goodsky datasheet that I found (attached), the following GU-SS-124DFS markings mean forType:GU= Quick Contact TabType of Sealing:SS= RT ? Flux Proofed RelaysNumber of Pole:1= One PoleCoil Voltage:24= 24V coilCoil Type:D= Standard DC CoilContact form: =nilOne Form CTerminal Type:F= Both PCB Terminal & Quick Contact TabsCase Type:S= With Flanged CaseInsulation System:nilStandard ClassSince the Contact form is nil (one form C), that implies it is a SPDT as per datasheet.Here is where I'm confused.In the Contact Rating table, page 1, under the column GU (D), it specifiesNC: 10A 240VACNO: 20A 240VACHowever, the photo showsNC: 20A/240VACNO: 30A/240VACThe website tohttp://www.goodsky.com.tw/is always down when I try to access it to find more information.Question 1) Which is correct? The datasheet or the markings on the actual relay?Question 2) If the photo is correct wrt to the contact ratings, then a search on mouser with the following parameters 30A relay, 24VDC coil voltage, SPDT, quick connect terminal yields 3 suitable candidates with W9AS5D52-24 being the most likely match.http://www.mouser.com/ds/2/357/105A_W9A-180345.pdfHowever, the datasheet (attached) specifiesNC: 15A/240VACNO: 30A/240VACIs the NC at 15A something to worry about? My friend has no means of measuring the amperage when the vending machine is running. He doesn't live in my city so I have no way of measuring it either.

author: jitter
author_rank: Frequent Contributor
timestamp: November 29, 2015, 09:23:55 am
content: Don't you just hate it when the markings and the datasheet contradict eachother?I'd probably use a "better safe than sorry" approach and replace the defect relay with a type of at least the same ratings as those in the photo.Having said that, I'd probably also take the failed relay apart to try and find out what caused it to fail. Did the relay fail because it just had its number of cycles and is end of life now, or was it not rated properly for the task? Did another fault take it out? How long was it in service?

author: Paul Moir
author_rank: Frequent Contributor
timestamp: November 29, 2015, 10:53:30 pm
content: Looking at google cached link:http://webcache.googleusercontent.com/search?q=cache:VaAtcXRpkZ0J:www.goodsky.com.tw/files/New%2520Datasheet/GU_QCT_relay.pdf+&cd=1&hl=en&ct=clnk&gl=ca&client=ubuntuit looks like they rerated the D to 20/30A. Note the file is in the "New Datasheet" directory.(Hard to read since not PDF, but I can't find a newer version elsewhere)I'd be thinking about why it died too, probably the one you linked it better.I wouldn't worry much about the NC contact's rating since it doesn't appear to be used in your picture!

author: retiredcaps
author_rank: Super Contributor
timestamp: November 30, 2015, 06:15:54 am
content: Quote from: jitter on November 29, 2015, 09:23:55 amThanks for responding.Since I'm still getting the hang of all the terminology and learning what parameters are important, I wasn't sure if I was interpreting the datasheet correctly and thus all my homework and questions.I probably won't be able to inspect the relay and unless I go on a road trip in the near future. I do have 3 other boards from him and all failed in the same way.; an obviously blown MOV. Getting replacements for those were easy.QuoteI agree.QuoteAs for all the other questions, I haven't heard back since the initial request to get a replacement. Some of his machines are very old so it could have just worn out.

author: retiredcaps
author_rank: Super Contributor
timestamp: November 30, 2015, 06:20:18 am
content: Quote from: Paul Moir on November 29, 2015, 10:53:30 pmFunny, I tried the cached trick before my post, but I still couldn't access anything on their site. But the link you provided is exactly what I was looking for and explains the discrepancy. Your search expertise has save me a lot of grief and sanity. I appreciate itAttached here for others in the future.QuoteThanks for answering Question 2 above. I will confirm that NC is not being used as per picture. I'm tempted to replace the SPDT with a SPST (one form A) since finding a 30A relay is way easier, but I have no idea if the NC connection is in the vending machine for other future purposes or not.