Return-Path: Delivered-To: craig@dapaero.com Received: from gator4254.hostgator.com by gator4254.hostgator.com with LMTP id 4Hy7MrspUGNeAwQAcizydQ (envelope-from ) for ; Wed, 19 Oct 2022 11:45:47 -0500 Return-path: Envelope-to: craig@dapaero.com Delivery-date: Wed, 19 Oct 2022 11:45:47 -0500 Received: from smtprelay0147.b.hostedemail.com ([64.98.42.147]:54934 helo=smtprelay.b.hostedemail.com) by gator4254.hostgator.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1olCCR-001757-Bq for craig@dapaero.com; Wed, 19 Oct 2022 11:45:47 -0500 Received: from omf12.b.hostedemail.com (10.5.19.248.rfc1918.com [10.5.19.248]) by smtprelay01.b.hostedemail.com (Postfix) with ESMTP id C91EF18A50000 for ; Wed, 19 Oct 2022 16:45:37 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: andrewscc@nctv.com) by omf12.b.hostedemail.com (Postfix) with ESMTPA id 831511807016F for ; Wed, 19 Oct 2022 16:45:37 +0000 (UTC) MIME-Version: 1.0 Date: Wed, 19 Oct 2022 09:45:37 -0700 From: Curt Andrews To: DAP AERO Subject: Re: 36 VDC 8000 watt inverter-1184 In-Reply-To: <8735A325-F490-4E4F-80EA-4EE66261EEF8@dapaero.com> References: <990D725C-A4FD-4469-A3C5-0E7C50532EF4@dapaero.com> <8735A325-F490-4E4F-80EA-4EE66261EEF8@dapaero.com> Message-ID: X-Sender: andrewscc@nctv.com Content-Type: multipart/alternative; boundary="=_b5657d30e5ba86631e87595a165f0370" X-Spam-Status: No, score=-5.10 X-Stat-Signature: 3h54j3pbhujykysrhofrp83cuazrctoi X-Rspamd-Server: rspamout04 X-Rspamd-Queue-Id: 831511807016F X-Session-Marker: 616E64726577736363406E6374762E636F6D X-Session-ID: U2FsdGVkX19Kh77+nve146PkTcI2njx8JoLvgbWb7b0= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nctv.com; h=mime-version:date:from:to:subject:in-reply-to:references:message-id:content-type; s=mail; bh=c3nMuYWfqlTbFPu9+WSaLbeWxS+vVz5b8fkDNF0pn40=; b=MTwK6UEjyG5SkDa/hABehQzHrCXp2QxF2u5IeRJk+v3NjfNA/bSjuoSpd4ilLDD+CnfujmOK1TMd3LxaPclR4jUV32lKcfDiR1xIs6LF3zxZBP9T6JEQvzDymrZJh7b+eG7cBeooEQVnRuEkhUgQDA47SrvOZ8oO7p78jVNITFhs1LAroKSW83pAfWyZm2W19IUwN3i6lWxacuIzQPxbDHRUveXlZqFtMgzQ8SkTzGeCGEkALWjNJCCoKQz6i4oOV862ALgF3Hef1IIEAyn/NVWb7d0seQmQrSH+7cfuskEVw986RcmVj5T7dRJz58aP1ujx5IqKlsWNKk0YH7lc0g== X-HE-Tag: 1666197937-608718 X-Spam-Status: No, score=0.2 X-Spam-Score: 2 X-Spam-Bar: / X-Spam-Flag: NO --=_b5657d30e5ba86631e87595a165f0370 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; format=flowed I do not think they know what the problem is, but i have two failed units and they hesitate to replace again. The first one I ran for a few hours and it totally burnt out four of the 12 large mofets on the back side. I have that one all torn apart. They sent a replacement and i turned it on and the 5 watt resistor started to smoke immediately and i turned it off. so it is still intact. So you can live test that one. The problem in the second unit is in the control circuity, not the high amp stuff. Something in the controls is simply pulling too much load through the resistor. I would ask for my $1200 back, but i have not found another manufacturer of a 36 volt pure sine wave inverter over 5000 watts. Everyone has gone to 48 volts. --- Curt Andrews 1336 E Oak Othello WA 99344 509 346 8108 On 2022-10-18 19:25, DAP AERO wrote: > If 4 more it is an H bridge so it is directly driving the big > transforme, probably like this > > https://www.homemade-circuits.com/easy-h-bridge-mosfet-driver-circuit-for-inverters-and-motors/ > > They must be confident the problem is not in the H bridge part > >> On Oct 18, 2022, at 7:19 PM, DAP AERO wrote: > > Oh wait, are there four more of these mounted on the other side of the > board? > > On Oct 18, 2022, at 7:12 PM, DAP AERO wrote: > > https://www.vishay.com/docs/91054/91054.pdf > > Gate should be isolated from other two leads > Freewheeling diode from source to drain, maybe 2v drop in diode test. > diode is reversed from drain to source so diode test should show no > current. > > In operation, the drain to source current is nearly zero until the gate > voltage gets between 2 and 4 volts and the source/drain resistance will > quickly go down as gate voltage increases. When the device is full on, > the source/drain resistance will be less than 0.5 ohm. > > Maximum source/drain current is 10 amps but that will dissipate 55 > watts from the internal 0.55 ohm resistance so it can only be on for a > moment to drive current into the step up transformer. It then turns > off, probably switches on and off in the kHz range and adjusts this > frequency and duty cycle to get your AC output of the inverter. > > Frequency is very high so transformer is smaller than you are probably > expecting. > > On Oct 18, 2022, at 6:41 PM, Curtis Andrews wrote: > > RF740 --=_b5657d30e5ba86631e87595a165f0370 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=UTF-8

I do not think they know what the problem is, but i have two failed unit= s and they hesitate to replace again. 
The first one I ran for a = few hours and it totally burnt out four of the 12 large mofets on the back = side.  I have that one all torn apart.  
They sent a re= placement and i turned it on and the 5 watt resistor started to smoke immed= iately and i turned it off. so it is still intact.  So you can live te= st that one.
The problem in the second unit is in the control circuity= , not the high amp stuff.  Something in the controls  is simply p= ulling too much load through the resistor. 

I would ask fo= r my $1200 back, but i have not found another manufacturer of a 36 volt pur= e sine wave inverter over 5000 watts.  Everyone has gone to 48 volts.&= nbsp;      

---
= Curt Andrews
1336 E Oak
Othello WA 99344
509 346 8108

On 2022-10-18 19:25, DAP AERO wrote:

 
If 4 more it is an H bridge so it is directly driving the = big transforme, probably like this
 
 
They must be confident the problem is not in the H bridge = part

On Oct 18, 2022, at 7:19 PM, DAP AERO <craig@dapaer= o.com> wrote:

 
Oh wait, are there four more of these mounted on the other= side of the board?

On Oct 18, 2022, at 7:12 PM, DAP AERO <craig@dapaer= o.com> wrote:

 
 
Gate should be isolated from other two leads
Freewheeling diode from source to drain, maybe 2v drop in = diode test.
diode is reversed from drain to source so diode test shoul= d show no current. 
 
In operation, the drain to source current is nearly zero u= ntil the gate voltage gets between 2 and 4 volts and the source/drain resis= tance will quickly go down as gate voltage increases. When the device is fu= ll on, the source/drain resistance will be less than 0.5 ohm.
 
Maximum source/drain current is 10 amps but that will diss= ipate 55 watts from the internal 0.55 ohm resistance so it can only be on f= or a moment to drive current into the step up transformer.  It then tu= rns off, probably switches on and off in the kHz range and adjusts this fre= quency and duty cycle to get your AC output of the inverter. 
 
Frequency is very high so transformer is smaller than you = are probably expecting. 

On Oct 18, 2022, at 6:41 PM, Curtis Andrews <andrew= scc@nctv.com> wrote:

RF740
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