I have an access point "AIR-AP2802I-I-K9" and I need a power injector for it. It is very hard for me to wait till import process. I need to operate it within a week urgent. Is there any other injectors (non-Cisco) could be used temporary?
check the local market if you can get one as below specification :
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Further to what @Leo Laohoo said - 30W and it must support CDP or LLDP
And as @AdamF1 said a cheap switch could also work but it would still need to support CDP or LLDP.
It must be 802.3at standard compliant.
So you could try something like https://www.tp-link.com/uk/business-networking/accessory/tl-poe160s/ but only testing will prove whether it works or not.
CDP/LLDP is a requirement for any 802.3at Type-2 PD device which requires more than 12.95 watts of input power - check the standard!
CDP or LLDP is used by all the Cisco Wave 2 and later APs to request the required power.
If they can't use CDP/LLDP then some may fall back to using 802.3af with max of 15W.
Some APs will work (to some extent) with that, some won't, some will scale back power draw by disabling eg USB port, some will disable some or all radios so that you can manage the AP but it has no or reduced (low power) output.
Read the data sheet for this AP - it's quite clear and very specific: https://www.cisco.com/c/en/us/products/collateral/wireless/aironet-2800-series-access-points/datasheet-c78-736497.html#Productspecifications
Input power requirements:
● 802.3at PoE+, Cisco Universal PoE (Cisco UPOE ®)
● 802.3at power injector (AIR-PWRINJ6=)
● 22.5W at the PSE (20W at the PD) with all features enabled except for the USB 2.0 port
● 26.5W at the PSE (23W at the PD) with the USB 2.0 port enabled
So minimum required power draw is 22.5W which means it will not function correctly without CDP or LLDP which is why Input power requirements states 802.3at PoE+, no mention of 802.3af.
Nice (oldish) summary of 802.3af/802.3at at https://www.ieee.li/pdf/viewgraphs/introduction_to_poe_802.3af_802.3at.pdf and https://www.microsemi.com/document-portal/doc_download/24-understanding-ieee802-3at-poeplus