Powerex Medical Scroll Controller

Regulated equipment (NFPA 99, CSA Z7396.1 in Canada). Any wiring or logic change must be documented and re-verified by a qualified medical gas installer.

Manufacturer

Powerex

Display

2-line 20-char LCD or color touchscreen (newer builds).

Years produced

~2005 – present, multiple hardware generations.

Power supply

24 VDC control, 120 VAC input.

Ambient range

5 – 40 °C (indoor equipment room).

Protection rating

IP54 front.

Relay outputs

One contactor coil per scroll head + dryer + alarm + BMS common trouble.

Used on

Powerex SES/SGP medical air skids
Powerex laboratory air packages
OEM-supplied to hospital projects

Features

Head lead-lag with hour equalization
NFPA 99 compliance logging
Automatic changeover if a head fails
Dewpoint & CO alarm outputs to Master Alarm Panel

Interfaces

RS-485 Modbus RTU
Dry contacts for BMS
NFPA 99 remote alarm panel outputs

Sensor inputs

Per-scroll head discharge temp
System pressure (4–20 mA)
Dewpoint (NFPA 99 medical air)
CO / CO2 monitors (integrated on medical air skids)

Common fault codes

Head Temp High (n)Scroll head n discharge over setpoint.

First checks

Head cooling fan operation
Inlet filter
Verify thermistor

See trigger conditions & affected models →

High Dewpoint Dryer outlet dewpoint above NFPA 99 limit (typ. +35 °F PDP).

First checks

Dryer capacity vs demand
Purge on desiccant units
Verify dewpoint sensor calibration

See trigger conditions & affected models →

Head Fail (n)Head commanded but no current / no pressure rise.

First checks

Contactor + overload for that head
Motor winding continuity
Auto-changeover to next head confirmed?

See trigger conditions & affected models →

System Reserve Low Reserve pressure below NFPA setpoint (typ. 40 psi below normal).

First checks

Increased demand event
Check all heads running
Leaks downstream of dryers

See trigger conditions & affected models →

Fault list is non-exhaustive and firmware-dependent. Always confirm against the controller’s on-screen help or OEM manual.

Wiring notes

Two independent power feeds required by NFPA 99 — one per side of duplex/simplex skid
Alarm outputs must be wired to Master Alarm Panel per NFPA 99 §5.1.9
Never bypass the dewpoint or CO alarm outputs — code violation

Known issues & field notes

Hour equalization drifts if a head is manually disabled — reset lead pointer after service
Firmware differences between medical & lab builds — do not cross-flash

Service menu password on modern touchscreen builds defaults to 1234 but MUST be changed at commissioning per hospital policy. Older LCD units used a hidden key combo (Set + Up + Down held 5s).

Manuals & literature

Powerex — support portal

Manuals hosted per-product — search model below

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Your manuals