Power rail: verschil tussen versies
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As the implementation for the power rail in the printer room uses double-through Fujitsu relays, their contacts are connected in parallel to reduce the current load. | As the implementation for the power rail in the printer room uses double-through Fujitsu relays, their contacts are connected in parallel to reduce the current load. | ||
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Versie van 1 mei 2017 om 18:07
After comissioning the 230V power rail on the back wall of the "3d-printer" room, an idea came about of making it remote-controlled for an easy remote poweroff. Taking into account potential scaling up to other nodes at MSL, where there may be no line-of-sight access for radio- or IR-remote, a decision was made to use MQTT over WiFi with ESP8266 as hardware.
Both L and N wires were to be switched independently, so two relays capable of switching 16A @ 230Vac were needed. These commonly come with coil voltages of 12Vdc and higher.
At the same time, ESP8266 runs nominally on 3.3V, but takes 5V via a LM1777 3.3v regulator. Going higher (to 12Vdc) was considered not recommended, as the SMD regulator would then dissipate too much heat.
Meeting both requirements above, we went with Fujitsu K1CK005W 5Vdc relays [1], while the SLA-05VDC-SL-A relays from AliExpress [2] were in transit. This way, we need only one 230Vac->5Vdc supply for both the ESP and the relays.
For this purpose, HLK-PM01 power brick [3], delivering 3W, was sufficient (~1W for ESP, plus ~1W per relay).
As the implementation for the power rail in the printer room uses double-through Fujitsu relays, their contacts are connected in parallel to reduce the current load.
