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Electrical
- Apr 18, 2020
- 29
Hi All,
Back in October I got a maintenance report on a Vertiv CP70Z 60 kVA UPS that said it had evidence of tin whiskering and needed cleaned. A batch of CP70Zs a few years ago had some metallurgical fault on the inverter bridge that allowed tin whiskers to form and grow long enough to clear the minimum arcing distance between the DC voltage feeding the inverter and the neutral. All of this model I have with this fault have all been fixed by Vertiv by ramming a plastic shim between the live and neutral.
I mailed Vertiv asking if they could clarify how much of a problem it was and if cleaning had to be scheduled but as usual they didn't reply.
In the mean time I was speaking to the guy I work with who was present during the maintenance, who said that the tin whiskering is really, quite egregious and very bad but hidden behind the covers we're not allowed to remove when the UPS is energised. He also said that he and the Vertiv guy witnessed the UPS throw itself in and out of an "IGBT desaturation" fault a few times but that this was not recorded on the event log. He said he made a decision not to tell anybody because "he thought it would be alright", and there's no mention of it on the maintenance report which says aside from the whiskering, it's in a very good condition. My colleague is a strange man and he's refused to talk about it any more.
I then caught up with the Vertiv Maintenance Manager during a meeting on another subject and managed to ask him if spurious unrecorded IGBT desat faults were possible, to which he responded that they are, and that it may be happening if the tin whiskering on the UPS inverter bridge allows an arc to form but the energy destroys the tin whisker before a catastrophic amount of energy can build up. Unsurprisingly after I asked him to check with the Vertiv engineer who performed the maintenance whether my colleague's story is true or not, I have not got a reply in a fortnight.
Now my question is this - should I be worried? I have nothing but the word of one man at work who is widely regarded as knowledgeable on the subject of UPSes but also a complete and utter basket case. One other person witnessed my colleague say this and he's happy to back me up. My primary concern is that a number of people go in to the room with the UPS and I myself have also been in there and opened the cabinet to try and see the tin whiskering. I do not appreciate the possibility that it could have thrown itself into fault or plausibly arced while I was doing that, as since I wasn't switching anything I was not provided arc flash PPE and had my shirt and tie on at the time.
On another note - does anybody else use Vertiv CP70Zs? Three of them have blown up at work in the last 2 years and my impression of Vertiv is pretty poor, just wondering if anybody else has had the same experience with them.
Thanks in advance.
Back in October I got a maintenance report on a Vertiv CP70Z 60 kVA UPS that said it had evidence of tin whiskering and needed cleaned. A batch of CP70Zs a few years ago had some metallurgical fault on the inverter bridge that allowed tin whiskers to form and grow long enough to clear the minimum arcing distance between the DC voltage feeding the inverter and the neutral. All of this model I have with this fault have all been fixed by Vertiv by ramming a plastic shim between the live and neutral.
I mailed Vertiv asking if they could clarify how much of a problem it was and if cleaning had to be scheduled but as usual they didn't reply.
In the mean time I was speaking to the guy I work with who was present during the maintenance, who said that the tin whiskering is really, quite egregious and very bad but hidden behind the covers we're not allowed to remove when the UPS is energised. He also said that he and the Vertiv guy witnessed the UPS throw itself in and out of an "IGBT desaturation" fault a few times but that this was not recorded on the event log. He said he made a decision not to tell anybody because "he thought it would be alright", and there's no mention of it on the maintenance report which says aside from the whiskering, it's in a very good condition. My colleague is a strange man and he's refused to talk about it any more.
I then caught up with the Vertiv Maintenance Manager during a meeting on another subject and managed to ask him if spurious unrecorded IGBT desat faults were possible, to which he responded that they are, and that it may be happening if the tin whiskering on the UPS inverter bridge allows an arc to form but the energy destroys the tin whisker before a catastrophic amount of energy can build up. Unsurprisingly after I asked him to check with the Vertiv engineer who performed the maintenance whether my colleague's story is true or not, I have not got a reply in a fortnight.
Now my question is this - should I be worried? I have nothing but the word of one man at work who is widely regarded as knowledgeable on the subject of UPSes but also a complete and utter basket case. One other person witnessed my colleague say this and he's happy to back me up. My primary concern is that a number of people go in to the room with the UPS and I myself have also been in there and opened the cabinet to try and see the tin whiskering. I do not appreciate the possibility that it could have thrown itself into fault or plausibly arced while I was doing that, as since I wasn't switching anything I was not provided arc flash PPE and had my shirt and tie on at the time.
On another note - does anybody else use Vertiv CP70Zs? Three of them have blown up at work in the last 2 years and my impression of Vertiv is pretty poor, just wondering if anybody else has had the same experience with them.
Thanks in advance.
