K-Tek M7A-MT5

Technical Dossier

Product Details And Specifications

K-TEK M7A Series Technical Notes

The K-TEK M7A series represents a mature line of magnetostrictive level transmitter electronics modules deployed extensively across global heavy industry — including petrochemical refineries, offshore platforms, chemical processing plants, and nuclear auxiliary systems. The M7A electronics platform interfaces directly with K-TEK's magnetostrictive level sensors, converting position data into standardized process signals (4–20 mA HART) for integration with distributed control systems (DCS) and programmable logic controllers (PLC). Its compact DIN-rail and head-mount form factors have made it a standard specification in brownfield plant environments where retrofit compatibility is a primary engineering constraint.

The Evolution of M7A Architecture

The M7A electronics module was introduced as the successor to K-TEK's earlier analog-only transmitter heads, adding HART digital communication capability to the existing 4–20 mA output infrastructure. Early M7A variants supported single-variable output (level only). Subsequent revisions introduced multi-variable output capability, enabling simultaneous transmission of level, interface, and temperature data over a single wire pair — a critical advancement for custody transfer and separator applications.

M7A Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly deployed models within the K-TEK M7A electronics series. Units are categorized by output type and functional configuration:

HART Transmitter Modules

• M7A-MT5: Multi-variable HART 5 transmitter module; outputs level, interface, and temperature simultaneously over 4–20 mA loop.
• M7A-MT7: Multi-variable HART 7 transmitter module; enhanced digital diagnostics and device description (DD) library support.
• M7A-ST5: Single-variable HART 5 transmitter; level output only; suited for simple tank gauging applications.
• M7A-ST7: Single-variable HART 7 transmitter; updated protocol stack with Wireless HART gateway compatibility.
• M7A-MT5-IS: Intrinsically safe variant of M7A-MT5; certified for Zone 0/1 hazardous area installation (ATEX/IECEx).
• M7A-MT7-IS: Intrinsically safe HART 7 multi-variable module; dual-seal housing for offshore and subsea-adjacent applications.

Analog Output Modules

• M7A-SA: Standard analog 4–20 mA single-variable output; no HART; legacy DCS compatibility.
• M7A-DA: Dual analog output module; independent 4–20 mA channels for level and interface; no digital protocol.
• M7A-SA-IS: Intrinsically safe analog single-variable module; barrier-compatible for Division 1 installations.

Foundation Fieldbus & Digital Protocol Modules

• M7A-FF: Foundation Fieldbus H1 transmitter module; supports multi-variable function blocks; for advanced DCS integration.
• M7A-PA: PROFIBUS PA transmitter module; compatible with Siemens and ABB PROFIBUS DP/PA segment couplers.

Display & Indicator Modules

• M7A-LCD: Local LCD display module; mounts to M7A transmitter head; shows level, interface, and temperature in engineering units.
• M7A-IND: Remote indicator module; 4–20 mA loop-powered; panel-mount for control room display.

Power Supply & Auxiliary Modules

• M7A-PSU-24: 24 VDC loop power supply module; DIN-rail mount; for non-self-powered sensor head configurations.
• M7A-TB: Terminal block assembly module; field-wiring interface for M7A head-mount installations; includes surge protection.
• M7A-CAL: Calibration interface module; used with HART communicator or PC-based configuration software for span and zero adjustment.

Quality Control for the M7A Range

The M7A electronics module integrates a precision analog front-end with a HART modem and microcontroller-based signal processing stack. Quality verification for refurbished or aftermarket M7A units requires protocol-level testing beyond basic continuity checks. DriveKNMS applies the following test procedures to all M7A modules prior to shipment:

• HART Communication Verification: Each module is connected to a calibrated HART master (Emerson 475 or equivalent) and queried for device identity, variable mapping, and diagnostic status registers.
• 4–20 mA Output Linearity Test: Output current is measured at 0%, 25%, 50%, 75%, and 100% of calibrated span using a precision current meter (±0.01 mA resolution). Linearity error must be within ±0.1% of span.
• Multi-Variable Output Validation: For MT5/MT7 variants, all three output variables (level, interface, temperature) are verified against known reference inputs using a magnetostrictive sensor simulator.
• Insulation Resistance Test: 500 VDC megohm test applied between signal terminals and housing ground. Minimum acceptable: 100 MΩ.
• Environmental Stress Screening: Units are cycled through operational temperature range (−40°C to +85°C) for a minimum of 4 hours to screen for latent thermal failures.
• Firmware Version Audit: Firmware revision is logged and compared against known stable releases. Units with corrupted or non-standard firmware are reflashed or quarantined.