| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 1411.1 | OK if Vin is 120VAC. | KALI::TOWNLEY | | Mon Sep 12 1994 15:48 | 8 |
| Hi, The DEChub ONE specifies its leakage current as not more than .75ma
@264VAC 50HZ, as well as the DEChub 900 supply. At 120Vac the readings
for leakage current would 1/2. This means that if the customers
Voltage source is 240Vac (like in Europe) we most likey to not meet
the 500ua max current requirement. But if the source is 120Vac
(US/Canada) than we meet this requirement of less than 500ua.
Regards, Tom
|
| 1411.2 | more | KALI::TOWNLEY | | Mon Sep 12 1994 18:05 | 4 |
| Hi,
Actual measurements by our safety group were less than
500ua @250VAC on the DEChub ONE.
Regards, Tom
|
| 1411.3 | One down and one to go. | CGOS01::DMARLOWE | Have you been HUBbed lately? | Mon Sep 12 1994 22:15 | 7 |
| Excellent. And the 900MS?
Keep this up and I'll owe you a couple of cool ones. That is if
I ever get down to Mass. assuming any more Network Symposiums in
the future.
dave
|
| 1411.4 | Some measured values. | CGOS01::DMARLOWE | Have you been HUBbed lately? | Tue Sep 13 1994 18:26 | 13 |
| I just did a couple of tests with a 900MS and 1 and 2 power supplies.
I did both a AC current to building ground and also voltage drop
thru a 1000 ohm resister for a double check.
The DEChub ONE was in fact around 200-230uA. Looks good.
The 900MS did not do so well. With one power supply it averaged
around 550 uA. 2 power supplies came out to 780 uA.
Are these values typical? Can anything be done to lower the single
power supply to less than 500 uA?
dave
|
| 1411.5 | Reasonable readings | KALVIN::TOWNLEY | | Thu Sep 15 1994 13:31 | 10 |
| Hi,
The DEChub 900 has some internal AC filtering that adds 200-230ua
to the power supply readings, this cannot be changed. The good news
is though this number does not change from 1 to 4 power supplies
attached. The total leakage current est is;
I(L)= I(DEChub900) + #PS X 200-230ua
= 200-230ua + #ps(1-4) x 200-230ua
Regards, Tom
|
| 1411.6 | Clairification... | CGOS01::DMARLOWE | Have you been HUBbed lately? | Thu Sep 15 1994 13:50 | 14 |
| My readings indicate that 1 supply yields 500-550 uA but 2 supplies
yields ~780 uA and so one. 4 supplies should yield 230 (hub) + 230 +
230 + 230 + 230 for a total of 1,250 uA. Assuming the theory is
right.
Since each supply is an entity unto itself, shouldn't they each
add a little ground leakage? If they shouldn't then maybe we can
talk offline about this.
The hospital even tests PC's and only the ones less that 500 uA
are kept. Actually they will accept 600 uA tops but prefer 500
uA.
dave
|
| 1411.7 | I(L) | NETCAD::TOWNLEY | | Tue Sep 20 1994 16:40 | 5 |
| Hi,
I'm not sure what you mean by add a little ground leakage, the
theory is right, the total leakage current per supply is independent
of how many are connected.
Regards, Tom
|
| 1411.8 | Finger in dike to stop leakage. | CGOOA::MARLOWE | Advanced Technology == MAGIC | Tue Sep 20 1994 17:53 | 6 |
| Each supply adds a "little leakage" until we get to around 1,200uA with
four supplies which is greater than the 500uA the hospital prefers but
will accept and the 600uA cutoff limit at which time they send the
equipment back to the manufacturer to be fixed.
dave
|