OMRON H3CT Series Timer Modules — H3CT-8H

Technical Dossier

Product Details And Specifications

OMRON H3CT Series: Comprehensive Module Range and Technical Overview

The OMRON H3CT series is a family of solid-state, multi-function analog timers engineered for continuous-duty industrial environments. Deployed across chemical processing plants, petroleum refineries, nuclear facility auxiliary systems, and heavy manufacturing lines, the H3CT has established a long-term installed base in applications where timing accuracy, panel-mount density, and relay output reliability are non-negotiable. The series operates on a plug-in 8-pin or 11-pin octal base, making it directly interchangeable with legacy electromechanical timing relays without rewiring. Its DIN-rail and surface-mount compatibility, combined with a wide supply voltage range, has made it a default specification in global OEM control panels for over three decades.

The Evolution of H3CT Architecture

The H3CT series was introduced as a direct solid-state replacement for OMRON's earlier electromechanical H3 timer line. Early production variants used analog RC timing circuits with a single time range and fixed operating mode. Subsequent revisions introduced multi-range dip-switch selection, expanding a single unit's coverage from milliseconds to hundreds of hours. The architecture then evolved to include multi-function mode selection — allowing a single SKU to be configured as on-delay (Type A), interval (Type B), or off-delay (Type C) — reducing the number of distinct part numbers required per panel design.

Compatibility across generations is maintained through the standardized 8-pin octal base (H3CT-8) and 11-pin base (H3CT-11) footprints. Panels designed for first-generation H3CT units accept current-production replacements without socket modification. As the series has entered its mature lifecycle phase, OMRON has transitioned primary production focus to the H3CR and H3DE digital timer families, positioning H3CT as a maintained-but-not-expanded platform. This makes long-term spare parts sourcing a critical operational consideration for facilities with existing H3CT installations.

H3CT Full Catalog & Functionalities (SKU List)

The following SKUs represent the verified H3CT series production range, classified by base type, time range, and operating mode. Each entry reflects a distinct catalog part number with defined functional characteristics.

8-Pin Octal Base Models (H3CT-8 Family)

H3CT-8H: On-delay timer, 8-pin octal base, 0.1 s–12 h multi-range, SPDT output, 100–240 VAC/DC supply.

H3CT-8H AC100-240: On-delay, 8-pin, factory-configured for 100–240 VAC, single time range per order code.

H3CT-8H DC12-48: On-delay, 8-pin, DC 12–48 V supply variant for low-voltage panel applications.

H3CT-8A: On-delay (Type A mode), 8-pin octal, 0.1 s–12 h, SPDT, wide-range supply.

H3CT-8B: Interval timer (Type B mode), 8-pin octal, output energized for set time period after trigger.

H3CT-8C: Off-delay timer (Type C mode), 8-pin octal, output de-energizes after set period following input removal.

H3CT-8D: On-delay with signal output (Type D), 8-pin, used in sequential start applications.

H3CT-8 AC/DC24: On-delay, 8-pin, 24 VAC/DC supply, standard in 24 V control architectures.

11-Pin Base Models (H3CT-11 Family)

H3CT-11H: On-delay timer, 11-pin base, 0.1 s–12 h multi-range, DPDT output, 100–240 VAC/DC.

H3CT-11A: On-delay (Type A), 11-pin, DPDT relay output for dual-circuit switching requirements.

H3CT-11B: Interval timer, 11-pin, DPDT output, suited for dual-load timed activation sequences.

H3CT-11C: Off-delay, 11-pin, DPDT, used where two independent circuits require simultaneous timed release.

H3CT-11 AC/DC24: On-delay, 11-pin, 24 VAC/DC supply, DPDT output for 24 V system integration.

H3CT-11D: On-delay with signal output, 11-pin, DPDT, for multi-circuit sequential control panels.

H3CT-8H-300: On-delay, 8-pin, extended time range to 300 hours, for long-cycle process timing in batch operations.

H3CT-8H-B: Combination on-delay/interval mode, 8-pin, field-selectable via front-panel switch.

Sourcing Hard-to-Find & Obsolete H3CT Parts

As OMRON has shifted its active development roadmap toward digital timer platforms (H3CR-A, H3DE-M), the H3CT series has transitioned into a lifecycle maintenance phase. Production runs are periodic rather than continuous, and certain sub-variants — particularly low-voltage DC models and extended time-range configurations — are no longer stocked at standard distribution channels.

DriveKNMS maintains a dedicated inventory program for H3CT series units sourced through verified industrial surplus channels, OEM decommissioning lots, and authorized secondary market suppliers. All units are cataloged by full part number, date code, and condition grade. For facilities operating legacy control panels with H3CT sockets, DriveKNMS provides direct cross-reference support to identify functional equivalents within the current OMRON catalog or compatible third-party alternatives where original units are no longer obtainable.

Quality Control for the H3CT Range

The H3CT series presents specific verification requirements due to its analog timing circuit architecture. Unlike digital timers with self-diagnostic outputs, H3CT units must be bench-tested across their full time-range dial positions to confirm calibration accuracy. DriveKNMS applies the following test protocol to all H3CT units prior to dispatch:

Timing accuracy verification is performed at a minimum of three dial positions per range band (low, mid, high) using a calibrated reference counter. Contact resistance of the SPDT or DPDT relay output is measured under rated load current to confirm contact integrity. Coil pickup and dropout voltage is tested against OMRON's published specification envelope. Insulation resistance between coil and contact circuits is verified at 500 VDC. Units exhibiting timing drift exceeding ±10% of set value, contact resistance above 100 mΩ, or insulation resistance below 100 MΩ are rejected and not offered for resale. Each passed unit is issued a test record traceable to its serial or date code.