Honeywell 621-9931 (6219931) Product Description

621-9931 (6219931) is the I/O Rack Power Supply module of the Honeywell 621 series, specially designed for traditional DCS systems such as IPC 620/621, UCN, TDC 3000, TPS, etc. It is used to provide stable and multi-channel DC power supply for the entire I/O rack and all the cards, and is the core power unit for the high reliability operation of the system. 

I. Basic Information

Brand: Honeywell (Honeywell / ISSC)

Full Model Number: 621-9931 (6219931)

Series: 621 Series I/O Rack Power Module

Type: Rack-mounted Multi-output Switching Power Supply

Production Status: Out of Production (Obsolete), Replacement Model: 621-9934C

Weight: Approximately 1.2 kg

Dimensions: Approximately 24.5 × 13.2 × 2.8 cm (standard 621 single-slot width)

Installation: Directly plugged into the dedicated power slot of the 621 Series I/O rack

Input: 115/230V AC automatic switching (wide voltage input)

Common Suffixes:

621-9931C: Enhanced, Long-life Capacitor Version

621-9931-RP: Refurbished / Repaired / Remanufactured Version

II. Core Functions

Multi-channel Voltage Stabilized Output: Provide +5V DC (Logic) and ±15V DC (Analog) three independent voltage stabilizations simultaneously

High Current Capacity: Satisfy the total power consumption demand of all modules in the fully configured I/O rack

Hot Swap Compatibility: Support online replacement (in conjunction with rack redundant power supply), without interrupting system operation

Comprehensive Protection: Overvoltage, Overcurrent, Short Circuit, Overheating, Reverse Polarity, Surge Full Protection

Status Monitoring: Real-time output voltage, temperature, fault status, supports remote system diagnosis

Redundancy Support: Can be configured with dual power supplies in 1+1 redundancy, achieving zero interruption power supply

System Compatibility: Compatible with IPC 620/621, UCN, TDC 3000, TPS, PlantScape systems

III. Electrical Specifications

Input Voltage: 115/230V AC (±15%), 50/60 Hz (automatically recognized)

Input Current: 6A @ 115V AC; 3A @ 230V AC

Output 1 (Logic): +5V DC / 8A (Power supply for the digital logic of the I/O module)

Output 2 (Positive Analog): +15V DC / 600mA

Output 3 (Negative Analog): -15V DC / 600mA

Output accuracy: ±1% (Full load, full temperature range)

Ripple noise: < 50mV p-p (5V); < 100mV p-p (±15V)

Efficiency: ≥ 82% (typical load)

Isolation voltage: 3000V AC RMS (Input - Output - Rack Ground)

Connectors:

Input: 3-pin terminal block (L/N/PE)

Output: 621 rack backplane dedicated bus connector

IV. Environmental Parameters

Operating temperature: 0°C ~ +60°C

Storage temperature: -40°C ~ +85°C

Humidity: 5–95% RH (no condensation)

Vibration resistance: 10–55 Hz, 0.7 mm double amplitude

Protection: IP20 (installed in the cabinet)

Certifications: CE, UL, CSA, 94V-0 flame retardant

VII. Status Indicators (LED)

PWR (Green): Input normal, main power working

5V (Green): +5V output normal

15V (Green): ±15V output normal

FAULT (Red): Overvoltage / Overcurrent / Overheat / Output failure

REDUND (Yellow): Redundancy mode activated (dual power supply)

VI. Typical Applications

621 I/O Rack Main Power Supply: Power supply for the I/O rack of IPC 620/621 system

UCN Network Power Supply: Universal Control Network remote I/O station power supply

DCS Redundant Power Supply: 1+1 redundant power supply configuration for TDC 3000 / TPS system

Power supply for Analog Modules: Provide precise ±15V analog power for AI/AO modules

Expansion of old systems: Power supply for the new I/O rack of 620/621 system

VIII. Model Comparison (621 Series Power Modules) Table

Parameters 621-9931 621-9934C 621-9920

Type I/O Rack Power Supply Replacement Upgrade Type Controller Power Supply

Output +5V/8A; ±15V/0.6A +5V/10A; ±15V/1A +5V/5A

Input 115/230V AC 115/230V AC 24V DC

Redundancy Supports 1+1 Supports 1+1 Not supported

Hot-swappable Supported Supported Not supported

Status Out of production In production Out of production

VIII. Common Faults and Troubleshooting

FAULT Red light constantly on

Reason: Output short circuit, overcurrent, module overheating, input voltage abnormal

Troubleshooting: Disconnect load → Reset power supply → Check input voltage → Replace module

5V or 15V light does not illuminate

Reason: Corresponding output overload, internal voltage regulation circuit failure

Troubleshooting: Reduce load, check module power consumption, replace power supply module

Dual power supplies not redundant (REDUND does not light up)

Reason: Other power supply failure, rack not enabled for redundancy, wiring error

Troubleshooting: Check dual power supply status, configure redundancy parameters, tighten backplane

IX. Related Models

Alternative model: 621-9934C (recommended)

Controller power supply: 621-9920 / 621-9921

Redundant power module: 621-9932 / 621-9933

I/O rack: 621-7000 / 621-7010 (14-slot rack)

Bus selector: 621-9929 / 621-9928