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[solved] CRS328-4C-20S-1S+ & CRS317-1G-16S+ internal voltage?

Posted: Tue Sep 11, 2018 6:47 pm
by AVA

I want to use the mentioned switches without the internal power supply (230V -> 24VDC) because we use UPS systems. Does anybody know if the switches run with 48V instead of 24V or do I need additional DCDC converters? The small CRS112 run with 10-57V.......

Thanks in adcance!


Re: CRS328-4C-20S-1S+ & CRS317-1G-16S+ internal voltage?

Posted: Mon Sep 24, 2018 2:21 pm
by AVA
Mikrotik Support told me: you have to use 24V.

Re: [solved] CRS328-4C-20S-1S+ & CRS317-1G-16S+ internal voltage?

Posted: Mon Sep 24, 2018 5:57 pm
by LEA
Only up to 24V (DC) with current consumption up to 2.5 Amps is possible.
1) In this case, it is better to use an uninterruptible power supply working with AC voltage in the range from 100 to 240 V

2) Uninterruptible DC power supply 24V with a value of 3 Amp support can also be found, only it will be necessary to take into account the losses along the length of the wire. Another source of uninterruptible power supply should be well stabilized in the voltage range of 22-24V.
The switching switching system must also be minimum discontinuous no more than 500 ms.
To do this, you will need a polar capacitor with a certain calculated capacitance for balancing the voltage transition from the working state from the network to the battery mode.

If you plan to use the second option, then you lose the warranty from the manufacturer!

Re: CRS328-4C-20S-1S+ & CRS317-1G-16S+ internal voltage?

Posted: Wed Aug 21, 2019 2:30 pm
by lekozs
Mikrotik Support told me: you have to use 24V.
I am powering older Mikrotik gear (like CCR 1036 8G-2S+ routers ) with a 24V setup using these:
- "Meanwell PSC-160B-C"
This is a 160W Single Output Power Supply with Battery Charger (UPS Function), with two 12Ah 12V (serially connected) batteries.
( )
It works for us without problems, for years...
Now... I was planning to use this setup for the CRS317-1G-16S+ when I stumbled across this thread.
The aforementioned Meanwell PSC-160B-C device's output voltage ranges from 21V up to 27.8V (21V is the cut off voltage to protect the battery, the 27.8V is the highest charging voltage)
As I mentioned all of the older Mikrotik devices are working flawlessly with this Meanwell power supply (CCR 1036, CCR 1009, CSS 326, CRS 326...)
Am I good to go with this setup on the CRS317-1G-16S+ also, or this device CAN NOT take voltage higher than 24V...?

Re: [solved] CRS328-4C-20S-1S+ & CRS317-1G-16S+ internal voltage?

Posted: Fri Aug 23, 2019 12:08 am
by marekm
The original question was about 48V. Such telecom power systems often have nominal -48V DC, negative voltage (positive ground) in range from 44V (low battery) to 55V (charging voltage, may be temperature-dependent - higher at low temperatures). Most MT devices expect +24V DC (negative ground) so you can't power it directly (that would cause a short-circuit), you need a DC/DC converter anyway to change polarity. If you have such a converter (isolated one like Meanwell SD-200C-24), it also provides stable output voltage regardless of battery charge. It would be nice to have more MT products support -48V DC input. Or at least design the power supplies in such a way that they also accept 48V DC input - with the usual active PFC input stage (step-up to about 400V DC which then powers the isolated DC/DC converter) this may not be that hard to do with some loss of efficiency (I have tested a few MT and UBNT devices with AC power supplies and found they start with 48V DC applied to AC input, but that is not guaranteed and I haven't tested for a long time at full power where something might overheat).