Designed to simplify pressure safety wiring for small and medium rooftop units.
General Description
Pressure safety wiring done right the first time!
- Ability to be reset by (1) external devices
- Wire up to (2) safety/other inputs
- General input status feedback
- Controls up to (4) fans
Both versions operate exactly the same. The PSR-124 is an ETL Recognized Component and is tested to UL 60730-1 and CSA E60730-1.
PSR-124 - $600
(UL 60730-1 &
CSA E60730-1 compliant)
PSR-124-NC - $450
Features
Power and Protection
The board can be powered with 24VAC/VDC. Once the board is powered a green LED labeled "Powered" will illuminate and the "Powered Status" contact will close. This contact will stay closed as long as the board has power.
The board and its internal components are protected by a fast acting glass fuse. The fuse is replaceable with a 5mm x 20mm glass fuse (3GA) rated for 250VAC @ 500mA.
Reset Functions
The board will enter and latch into an "alarm" state when any input is activated. When the board is in an "alarm" state a red LED labeled "Safety Tripped" will illuminate.
The board can be reset into its normal operation via:
- The on board push button (yellow button labeled with "Push to Reset") or
- Wiring a dry contact to the "Reset 1" terminal. The contact should close when a reset is requested.
- Please note that this input has voltage sourced from the board, so external voltage should not be supplied.
Inputs
The PSR-124(-NC) has two inputs. Ideally, these contacts should be wired to a safety or pressure switch that closes when a safety or abnormal pressure event occurs.
When a contact closure is applied to either input terminal, the board will latch into an "alarm" state. The only way to reset the board into normal operation is by performing one of the two reset options listed above.
These inputs have voltage sourced from the board, so external voltage should not be supplied to these contacts.
The external safety contact must be rated to handle 12VDC @ 0.5A.
Normally Closed Outputs
The PSR-124(-NC) has (4) outputs that can be wired Normally Open or Normally Closed. When either of the safety inputs are activated and the board goes into its "alarm" state the output contacts will move to their set position. The board will latch in this position until the board is reset.
Ideally, these contact should be wired to the safety or run permissive contacts on fan/motor VFDs. Which contact on the VFD and how this is wired fully depends on how the VFD is setup.
The outputs are rated at 0.5A @ 125VAC or 2A @ 30VDC.
High Amperage Master Relay
The Master relay is designed to be able to directly enable or disable small motors. The contacts on this relay is rated at 4A @ 120VAC and 3A @ 30VDC.
In normal board operation, the relay will be in its de-energized position. When the board is in "alarm" the relay will be energized. (i.e. the N/C contact will be open and the N/O contact will be closed.)
This relay can also be wired to externally mounted "normal operation" indicators and "alarm operation" indicators. Please refer to "PSR-124(-NC) example wiring" document for more information.
Input Alarm Status
The PSR-124(-NC) has one contact labeled "Input Alarm Status" that will close when the board is in an "alarm" state. During normal board operation, this contact will be open.
This contact can be wired to a BMS controller / other field controllers as a feedback point. (i.e. When this contact is closed, the VFDs hooked up to the PSR-124(-NC) outputs will be off.)
This contact is rated at 0.5A @ 125VAC or 2A @ 30VDC.