What are the relays state of ZBRRA receiver when powered off?
1. What you need to know
When a Harmony ZBRRA receiver has no supply voltage, both output relays sit in their de-energized position: the NC contacts 11-12 and 21-22 are closed, and the NO contacts outputs 12-14 and 22-24 are open. If the supply is cut off while an output is ON, the contacts outputs return to this same de-energized state. Output states are not retained through a power loss; transmitter pairing and the configured output mode are maintained.
2. Understanding the ZBRRA output behaviour
The ZBRRA is a programmable receiver in the Harmony XB5R (plastic) and XB4R (metal) wireless and battery less pushbutton range. It converts radio frames from ZBRT* wireless batteryless transmitters into dry contact outputs. Its two outputs are electromechanical changeover relays, so their unpowered position is a mechanical rest position, not a saved state.
3. Contact state according to receiver condition
| Receiver condition | NC contact (11-12 / 21-22) | NO contact (12-14 / 22-24) | Relay state |
|---|---|---|---|
| Not powered (supply off or lost) | Closed | Open | De-energized - default state |
| Powered, no command received | Closed | Open | De-energized |
| Powered, output ON in monostable mode | Open | Closed | Energized while the command is active |
| Powered, output ON in bistable or stop/start mode | Open | Closed | Energized until the next command |
| Supply lost while the output is ON | Closed | Open | De-energized - the ON state is not maintained |
| Supply restored | Closed | Open | De-energized until a new command is received |
4. Related references
| Function | Reference | Description |
|---|---|---|
| Programmable receiver | ZBRRA | 2 changeover relay outputs 3 A, 24-240 V AC/DC, monostable / bistable / stop-start, 6 indicating LEDs |
| Transmitter | ZBRT1 | Wireless and batteryless transmitter, without head |
| Transmitter head, plastic | ZB5RTA2 | ZB5R plastic pushbutton head, black cap, spring return |
| Transmitter head, metal | ZB4RTA2 | ZB4R metal pushbutton head, black cap, spring return |
| Visual feedback | ZBRV1 | Visual feedback module for ZBRT transmitters |
| Antenna | ZBRA1 | Relay antenna to extend radio range |
Download the instruction sheet from the product page on se.com, browse the current wireless offer in DigiCat, or contact Schneider Electric technical support to validate a layout before installation.
Released for: Schneider Electric Hong Kong
