Designed to simplify pressure safety wiring for medium and large rooftop units.
General Description
Pressure safety wiring done right the first time!
- Ability to be reset by (2) external devices
- Wire up to (4) safety inputs
- Individual input feedback
- Controls up to (8) fans
Both versions operate exactly the same. The PSR-248 is an ETL Recognized Component and is tested to UL 60730-1 and CSA E60730-1.
PSR-248 - $800
(UL 60730-1 & CSA
E60730-1 Certified)
PSR-248-NC - $650
Features
Power and Protection
The board can be powered with 24VAV/DC. 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 safety 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 #" terminals. The contact should close when a reset is requested.
- This input has voltage sourced from the board, so external voltage should not be supplied to this contact.
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-248(-NC) example wiring" document for more information.
Inputs
The PSR-248(-NC) has four 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 any of the input terminals, 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-248(-NC) has (8) outputs that can be wired Normally Open or Normally Closed. When any of the 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.
Input Alarm Status
The PSR-248(-NC) has individual safety status. This means that when the "Input 1" terminals are activated, the "Input 1 Alarm Status" contact will close. The PSR-248(-NC) board also has individual LED indicators for the all four input alarm status. During normal board operation, the "Input # Alarm Status" contact will be open.
These contact can be wired to a BMS controller / other field controllers as individual input feedback. Knowing which Input tripped the board can be used for diagnostic purposes to help determine the source of the problem. If access to the BMS is limited, the on board LED indicators for each input alarm will help field technicians determine the source.
These contacts are rated at 0.5A @ 125VAC or 2A @ 30VDC.