A few weeks ago, I wrote a blog post about two of our UL924 Emergency Lighting Bypass / Shunt Relays (models ESRB and ESRN). This week I want to focus on a specific application for them; one which shows up frequently. The ESRB and ESRN can be used in conjunction with a 0-10Vdc Dimming Control Panel and can control Emergency Lighting under normal conditions.
Under Normal Conditions, with the Lights ON
When the Lighting Control Module closes a single zone’s contact, the Normal Power feeds through to both the Normal Lighting loads as well as the ESRB/ESRN’s Switched Input. Even though the Normal/Emergency Lighting is being powered from the Emergency Panel, it is still controlled by the zone contact and 0-10Vdc signal on the controller. See image below for a wiring schematic:
Under Normal Conditions, with the Lights OFF
When the Lighting Control Module opens a single zone’s contact, the Normal Power stops at the open contact, and does not feeds voltage through to either the Normal Lighting loads or the ESRB/ESRN’s Switched Input. Even though the Normal/Emergency Lighting is being fed 0-10Vdc from the controller, the high voltage side of the load is broken by the ESRB/ESRN relay contact due to the lack of a control voltage on the Switched Input. See image below for a wiring schematic:
Under Normal Power Failure
When there is no Normal Power present, the Lighting Control Module cannot control either the zone contact or the ESRB/ESRN. The ESRB/ESRN notices the absence of Normal Power, and therefore passes the Emergency Power through the relay contact and out to the Normal/Emergency Lighting. Because there is 0V coming out of the controller, and because there is high voltage applied to the power input of the Emergency Lighting loads, the Normal/Emergency Lighting loads come on at full brightness. See image below for a wiring schematic:
Need more information on our full line UL924 Emergency Lighting Bypass / Shunt Relays? Give us a call or shoot us an email, and we’ll be happy to answer any of your questions.