My DC side MNSPD-300 has a very, very dim blue led. It's so dim that I thought it was out until I looked very closely in the dark. I've wired it according to the instructions and everything on the DC side works properly in my system.
By contrast, my AC-side MNSPD-300 is bright enough to read by.
I get from the directions that one of the two blue leds should be off on my DC-side arrestor since it's connected to the PV-.
But is it normal for the remaining led to be that dark? I'm guessing it is, but thought I'd check. Thanks!
During the daylight hours the LED should be as bright as the ones on the AC side. I would suggest pulling the lead off the PV- and hooking it to PV+ and see if it is as dim or if it is full brightness. This could be a sign of a bad ground at the SPD or a bad LED. The easiest way to test the SPD is to go to the car battery and touch the green on - and the red on + and then re test with the green on - and the black on +
Let us know the results
Ryan
Ryan,
Thanks, I just performed the tests:
Putting the PV- lead to PV+: no change.
Testing on a car battery: bright led with both + and - leads.
So the LED is fine.
Maybe there is a problem with my DC ground? I checked the connections out to the grounding electrode and it seemed o.k.
Here's one thing about the installation that might be relevant. I'm using a Magnum MMP panel and Magnum inverter. The MMP manual says to connect the DC arrestor by running the + and - leads directly to the inverter DC output, not to the + and - busbars. So that's what I did. (The ground lead goes to the ground busbar.)
Eric,
I had a similar issue with my SPD across the batt DC input on my Magnum 4448. Look at my previous posts on this topic. Resetting the Magnum fixed it (turn off all input power). You may want to do the the same with your equipment.
Robin/Ryan -- you guys have some idea what is causing this ? Is it the input voltage detection circuit on the inverter? I remember somebody reporting this also on a Xantrex.
Quote from: laszlo on March 19, 2012, 11:10:23 PM
Eric,
I had a similar issue with my SPD across the batt DC input on my Magnum 4448. Look at my previous posts on this topic. Resetting the Magnum fixed it (turn off all input power). You may want to do the the same with your equipment.
Robin/Ryan -- you guys have some idea what is causing this ? Is it the input voltage detection circuit on the inverter? I remember somebody reporting this also on a Xantrex.
Laszlo, this just doesn't make any sense to me... Unless, maybe the Magnum was drawing a LOT of current and
dragging down the battery voltage some. Was it running before you did the reset ?
What was the battery voltage at LED dimming time ?
The 4448 doesn't have any circuitry that should affect battery voltage at its DC terminals.
How exactly was your SPD connected to the 48 V DC input line again ??
boB
boB,
I can't answer for laszlo, but in my case it's just SPD ground to DC ground, red to DC + at the inverter's terminal, black to - at the terminal, using a 5/16" crimp-ring on each terminal connector.
This is how Magnum instructs for their MMP panel p. 60-1 of the manual:
http://www.magnumenergy.com/Products/MMP.htm
I noticed this weekend that when I turned off the PV input breaker to update my Classic, the led in the DC side SPD got bright. Then it went back to very dim when the Classic was turned back on.
Putting the SPD right at the inverter terminals is not a good place for them. Lightning comes in over power lines. This can be the PV array, utility, generator or house wiring. Putting the SPD right at the battery terminals is not as effective as putting it closer to where the surge is coming from. It is a good idea to have some distance (wiring resistance) between the SPD and the product to be protected. I typically ignore the battery circuit because the cables are very short and a battery bank is a pretty effective SPD all by itself. The SPD is pretty cheap insurance though and in some cases would protect your battery bank as well as the inverter. Use the MNSPD115 for battery circuits. Magnum may not have terminals to tie a SPD into on their circuit breaker boxes. They have not been in the circuit breaker box game as long as I have. We provide places to hook up lightning arrestors to every circuit that has the possibility of conducting a surge. AC IN, AC Out, PV IN, Battery Plus and Minus. That pretty well covers the possible entry points and still gives a little distance between the electronics and the SPD.