MidNite Surge Protective Device

JESSICA

Greetings:
I bought and installed the MidNite Solar Surge Protective Device. http://www.solar-electric.com/mnspd300.html
Installation: Green wire to Ground bus bar; Red wire to DC HOT IN in my mx60; and Black wire to NEGATIVE (WHITE) IN in my mx60.
According to the Manual, 2 LEDs in the device should glow blue when everything is alright. In my MNSPD no LEDs glow.
Did I do something wrong?

"The MidNite Solar surge protection device (SPD) is offered in three different models: MNSPD115, MNSPD300 and MNSPD600. The model you need will be determined by the voltage of the circuit being protected. The SPD is designed or AC and DC circuits for indoor and outdoor applications. These can be used on single devices or can be connected to an electrical load center. Blue LED indicators will light when voltage is present, showing you that your system is protected."

Cariboocoot

Re: MidNite Surge Protective Device

It may be the wrong model for battery Voltages. The 300 is designed for up to 300 VDC, the 115 for up to 90 VDC. The 115 is the one to use on battery Voltage. Assuming you have the battery connected the LED's may glow so dim as to not be visible. The 300 would be used on standard AC lines of 120/240 Volts.

If this is on the PV IN and you have a high Voltage array you'd use the 600 model. It's all a matter of matching the Voltage you're trying to protect.

Or of course in this universe of infinite possibilities it could be defective.
Nah.

JESSICA

Re: MidNite Surge Protective Device

Cariboocoot wrote: »

It may be the wrong model for battery Voltages. The 300 is designed for up to 300 VDC, the 115 for up to 90 VDC. The 115 is the one to use on battery Voltage. Assuming you have the battery connected the LED's may glow so dim as to not be visible. The 300 would be used on standard AC lines of 120/240 Volts.

If this is on the PV IN and you have a high Voltage array you'd use the 600 model. It's all a matter of matching the Voltage you're trying to protect.

Or of course in this universe of infinite possibilities it could be defective.
Nah.

If it is not defective, will it do it's job, even if it is not the right model? I mean, will/can it protect my cc and inverter in case of a lightning strike?'

In addition: Did I connected it the right way? (Both wires, red and black, each to + and - DC in terminals in my cc?

Cariboocoot

Re: MidNite Surge Protective Device

Your connection is correct: green to ground, black to negative, red to positive.

The protection is different on the two because of the different operating Voltage ranges. So you will have protection against surges/spikes with the 300 model, but they will be above the levels that would be handled by the 115.

Look at it like this:
300 is meant to run up to 470 Volts maximum. Anything above the "safe" level for that Voltage would be considered a spike and clamped.
115 is meant to run up to 180 Volts maximum. Anything above the "safe" level for that Voltage would be considered a spike and clamped.

As such, using the 300 on the lower Voltage system means you are "missing" an area of surge protection between 180 and 470 Volts. Most of the time this would not be a problem, as lightning strikes are well above these levels anyway. But strikes can cause elevated levels of stray Voltage in the area and may energize the wires to a level in this Voltage range which could be damaging to the equipment. This is pretty "iffy" (and also not the most technically accurate description :roll ).

By the way, you can connect the 300 to the AC out of your inverter and see if the LED's glow then: green to ground, black to neutral, red to hot. That should at least tell you if it is working.

Also the AC lines and PV lines are the ones that usually get "zapped". Were you putting this on the MX60's input or output?

JESSICA

Re: MidNite Surge Protective Device

Thanks for your help.

BTW: Your advise [By the way, you can connect the 300 to the AC out of your inverter and see if the LED's glow then: green to ground, black to neutral, red to hot. That should at least tell you if it is working.] is really good. I will do that.

niel

Re: MidNite Surge Protective Device

jessica,
the leds will not light in every protective circumstance. it will depend on the points where power is available in order to light the leds, but that does not mean the protection is not there because the leds are off. you can put the green wire to the battery - and put the other 2 wires to the battery + and both leds should light. should this not be the case then contact midnite. the ac test is also good to do. if the battery - is at ground potential then that would allow for 1 led to light with your original wiring. let us know what you find.

westbranch

Re: MidNite Surge Protective Device

here si a post over on the MidNite site that may be helpful http://midniteforum.com/index.php?topic=512.msg3166#msg3166

waynefromnscanada

Re: MidNite Surge Protective Device

JESSICA wrote: »

Installation: Green wire to Ground bus bar; Red wire to DC HOT IN in my mx60; and Black wire to NEGATIVE (WHITE) IN in my mx60.
According to the Manual, 2 LEDs in the device should glow blue when everything is alright. In my MNSPD no LEDs glow.
Did I do something wrong?

No, nothing wrong. Each LED will light IF the wire it is associated with is connected to a voltage source high enough. In your case, the positive input to your mX-60 is not high enough to obviously light the LED related to the Red wire. Furthermore, if your battery negative is grounded, there will be no voltage worth considering between ground and the MX-60 negative, therefore, as long as everything is operating properly, the LED associated with your Black wire will never light, can never light.
All is good. I have two of these same SPDs, both used on the AC outputs of my inverters, which have > hundred foot runs from the solar shed to the house. In both cases, the LED associated with the inverter HOT lights, while the one connected to grounded Neutral does not. Which begs the question - - if the neutral is already hardwired to ground, why do we need a surge protector to clamp it to ground in the event of a surge? Likewise the grounded negative of your MX-60 - - or mine?

Cariboocoot

Re: MidNite Surge Protective Device

Universal fit.

That particular model is meant to be installed on 120/240 VAC lines. In the case of the latter, the black goes to L1, the red to L2, and green to ground which is bonded to neutral. In this case you have Voltage potential between any two leads.

The MidNite people are smart. They accommodate the new DC ground fault rules under which the negative is not tied to ground. Once again you have Voltage potential on any two given wires.

Things can go wrong: one line can become unbonded from ground, but it still needs protection.

If you want to test it fully, use the AC method I mentioned before and switch the red and black on the hot wire. You should get one LED lit one way, the other with the wires reversed.

And it may not light either on battery Voltage because an LED takes very little Voltage to light so the supply from the expected has to be decreased. As the supply Voltage increases (115 to 300 to 600) the LED needs greater drop to prevent it burning out under normal operation. With lower Voltage available, that drop may be too much to light the LED.

Again, it will work in that application but it does leave out a range of Voltage spikes that could be harmful to lower Voltage components. Things meant to operate on 'line' Voltage tend to have a 300 or 600 Volt tolerance; things that are meant to operate at <60 Volts don't have that same high Voltage tolerance.

It's late in the day: this may not make sense.

boB

Re: MidNite Surge Protective Device

If your PV negative and/or Battery negative are grounded (connected together) then, if there is voltage on that hot PV wire, at least one LED should light up on
the SPD 300. If the negative(s) are not grounded, there will not be a path to light the LED(s). The LEDs do not need very much voltage to light up. I think
around 10 volts minimum.

The reason you need to protect the PV positive AND PV negative is that lightning is a common mode event and will raise both positive and negative
lines with respect to GND that the lightning is trying to get back to. If the negative is grounded right at the controller and inverter then an SPD
right there might very well be overdoing it a bit. This is why it is a good idea to also, or, sometimes instead to place the SPD closer to
the PV array itself. Of course both ends is good but it more expensive.

The SPD 600 is a bit different in that the LED circuit is connected from one hot to the other hot wire and not both wires to the green GND wire.
This is because when non-isolated inverters see the small LED current to ground, (1 mA), they may tend to trip their internal GFI circuit because
they think it is leakage.

JESSICA

Re: MidNite Surge Protective Device

Cariboocoot wrote: »

If you want to test it fully, use the AC method I mentioned before and switch the red and black on the hot wire. You should get one LED lit one way, the other with the wires reversed.

Again, it will work in that application but it does leave out a range of Voltage spikes that could be harmful to lower Voltage components. Things meant to operate on 'line' Voltage tend to have a 300 or 600 Volt tolerance; things that are meant to operate at <60 Volts don't have that same high Voltage tolerance.

It's late in the day: this may not make sense.

It did make sense.
I tested it according to your instructions, and, voilá, two beautiful blue LEDs shone as they should.
So, at least, I will not have to return it, just buy the right model next time.

Thanks to all of you.

JESSICA

Re: MidNite Surge Protective Device

Forgive me, but here I see some kind of contradiction:

Wayne wrote:

waynefromnscanada wrote: »

No, nothing wrong. Each LED will light IF the wire it is associated with is connected to a voltage source high enough. In your case, the positive input to your mX-60 is not high enough to obviously light the LED related to the Red wire. Furthermore, if your battery negative is grounded, there will be no voltage worth considering between ground and the MX-60 negative, therefore, as long as everything is operating properly, the LED associated with your Black wire will never light, can never light.

But BoB wrote:

"If your PV negative and/or Battery negative are grounded (connected together) then, if there is voltage on that hot PV wire, at least one LED should light up on the SPD 300. If the negative(s) are not grounded, there will not be a path to light the LED(s). The LEDs do not need very much voltage to light up. I think around 10 volts minimum."

In my case, my battery (-) is not itself grounded, because I grounded the (-) terminal of my Exeltech inverter. Nevertheless, no LED shone when I connected the Surge Protective Device to the DC side of the system.

BB.

Re: MidNite Surge Protective Device

Get or build a little test light... Something like one or two automotive brake lamp bulbs in series (i.e., 12 volt bulb vs 12/24/48 volt battery bank). And test your connection points between +/-/Safety ground.

If you have the DC GFI (fuse or breaker), going from +/- to earth ground may pop the fuse or trip the breaker--So be warned (and have extra fuses on hand).

Using a volt meter does not usually draw enough current for you to see if there are "real connections" vs the leakage current that can be present on any largish power system. The test lamps are a great way to safely "load" your system for testing.

-Bill

Cariboocoot

Re: MidNite Surge Protective Device

Voltage potential again.
When any part of the negative in a system is grounded essentially all of it is grounded, so the Voltage potential between (-) an G is zero (in theory). This means any sort of light connected between (-) and G will not light because there is no Voltage potential.

Exception time! Wire has resistance, so depending on where the ground bond is in relation to where the light is placed there can be Voltage potential and possibly enough to light the light.

On schematics all wires should be drawn as tiny zig-zag lines to indicate they are very small resistors.