Výpočet PoE rozpočtu pro NTP hodiny
Příliš málo PoE výkonu znamená hodiny, které odmítnou nastartovat. Předběžný výpočet zabrání výměně přepínače uprostřed projektu.
Per-clock consumption (Masterclock-rated)
| Model | Power | PoE class |
|---|---|---|
| NTDS44 (4-digit, single colour) | ~8 W | 802.3af |
| NTDS46 (6-digit, single colour) | ~12 W | 802.3af |
| NTDS112 (12-digit, single colour) | ~20 W | 802.3at (PoE+) |
| LUX26 (multicolour) | ~25 W | 802.3at (PoE+) |
| NTDS-DF (Double Faced) | 1.5× single | 802.3at or bt |
| NTDS-8AL / -12AL (multi-time-zone) | 25-40 W | 802.3bt (PoE++) |
- Add up consumption of all clocks
- Add 20% reserve for degradation and LLDP-negotiation overhead
- Compare with the total PoE budget of the switch (on the datasheet)
- Switches that support LLDP power-negotiation save budget — choose models that do
Cable-length impact
- Up to 80 m: standard Cat5e/6 is fine
- 80-100 m: voltage drop ~12% — requires PoE+ minimum (no 802.3af at that distance)
- >100 m: not supported by the PoE standard — use a PoE extender or fibre with a fibre-to-PoE converter
Switches we see working
- MikroTik CRS3xx series (budget-friendly, LLDP-PoE)
- Ubiquiti UniFi PoE switches (mid-range)
- Aruba 2540/2930 (enterprise, high reliability)
- Cisco Catalyst 9200/9300 (enterprise + 802.3bt)
Delivery by Daylight
We do not sell switches but we advise on the choice free of charge. Provide us with:
- Number of clocks per model
- Maximum cable length
- Preferred switch brand
Help with your installation?
Daylight bv supports on-site installations across Europe. Send us your site information and we will run a pre-installation check.
Contact Daylight