Views: 29 Author: Site Editor Publish Time: 2026-10-21 Origin: Site
TECHNICAL ARTICLE | INDUSTRIAL HARDWARE DESIGN
Compact True RMS Transmitter with a 90° Dual-Board Design
How a 24 mm DIN-rail profile, separated signal and power domains, and 2 kV three-port isolation improve cabinet integration
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Secondary keywords | 24mm DIN rail transmitter; 90-degree dual-board design; isolated AC/DC current voltage transmitter; 2kV isolation transmitter; space-saving DIN rail transmitter; JXK-D21U-Z |
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CABINET DESIGN AND HARDWARE RELIABILITY
Compact True RMS Transmitter with a 90° Dual-Board Design
How a 24 mm DIN-rail profile, separated signal and power domains, and 2 kV three-port isolation improve cabinet integration
Control cabinet layouts rarely fail for one dramatic reason. They become difficult because every added transmitter consumes rail length, wiring space, ventilation area, and access for service. When a panel grows from four measurement loops to twelve, a device that looked compact in a catalog can force changes to terminal placement, cable routing, and enclosure depth.
The JXK-D21U-Z takes a different approach. Its 90° dual-board architecture places signal acquisition on a side board and processing/output functions on a base board, within a 24 mm thin body and DIN35 rail clip. The compact true RMS transmitter for AC/DC current and voltage measurement is designed to reduce rail footprint while creating a clearer physical boundary between low-level input signals and power-conversion or output circuitry.
On a DIN rail, the nominal width of each device is only part of the space it needs. Terminal blocks, wire bend radius, labels, clearances, and screwdriver access all compete for the same area. A 24 mm device can allow more channels per rail, but the practical benefit appears when several units are mounted together: shorter wire runs, less congestion around terminal covers, and a more predictable cooling path.
Space also affects thermal behavior. Compact devices increase power density. If heat sources and sensitive analog circuits share the same board area, temperature gradients can increase offset drift and component stress. The mechanical layout is therefore part of measurement quality, not just an enclosure detail.
The base board runs parallel to the mounting plane and carries signal processing and output functions. The side board stands at 90 degrees and carries the signal acquisition input. This orthogonal arrangement uses the third dimension instead of extending the product's footprint across the rail. It also shortens the route from field terminals to the input stage and gives designers a visible boundary between acquisition and processing.
The two boards are tied together through a controlled assembly angle. Perpendicularity is not cosmetic. Connector alignment, board spacing, and isolation clearance all depend on it. A small angular error can stress a header, reduce creepage distance, or make a production test fixture unreliable. Controlling the assembly angle keeps those conditions repeatable from unit to unit.
Test pins on the side board provide defined access for production testing, calibration checks, and troubleshooting. External module contact surfaces also receive insulation protection where mechanical contact could otherwise compromise clearance. These details turn a compact assembly into a controlled manufacturing and service design.
The side board handles input acquisition, where low-level analog signals are most sensitive to noise and thermal gradients. The base board handles signal processing and output, where power conversion and output circuitry can create local heating and electromagnetic disturbance. Physically separating these domains reduces the opportunity for switching noise to couple directly into the measuring front end.
The product uses a dual power architecture built around F2415S and F2405S converter modules. Separate supply paths support different circuit sections instead of relying on one regulator chain. This arrangement helps local regulation, provides a clearer distribution of power losses, and limits the interaction between changing output-side loads and sensitive input circuitry. Voltage, loading, and thermal limits remain governed by the approved datasheet.
Design element | Implementation | Engineering consequence |
24 mm body profile | DIN35 rail clip | Reduces rail allocation and leaves room for wiring and service access |
90-degree dual-board build | Side board for input acquisition; base board for processing and output | Uses vertical space while separating sensitive and active circuitry |
Dual power architecture | F2415S and F2405S converter modules | Supports separate supply domains and more predictable local regulation |
Three-port isolation | DC 2 kV for 1 minute between input, output, and supply | Provides a defined, testable barrier between electrical domains |
Three-Port Isolation at DC 2 kV for One Minute
Three-port isolation separates the input, output, and auxiliary supply paths. The DC 2 kV for one-minute dielectric test verifies the insulation system between these domains under specified test conditions. It creates a defined barrier that helps protect low-voltage control electronics from faults or transients coupled through field wiring, and reduces the chance that a fault will propagate from one side of the measurement boundary to another.
The rating alone does not create isolation. Performance depends on conductor spacing, PCB slots, insulating materials, connector geometry, and the surfaces where an external module touches the assembly. The design combines the isolation barrier with controlled board spacing and insulated contact surfaces. Site wiring must preserve the same clearances. Contamination, moisture, exposed conductors, or careless cable routing can defeat an otherwise sound internal layout.
The 2 kV test value is not a continuous working voltage and does not replace surge protection or installation standards. Designers should verify pollution degree, altitude, overvoltage category, and the final enclosure requirements for the application. The value is useful because it establishes a repeatable proof test, not because it removes the need for system-level protection.
With two boards in a small enclosure, heat spreading and airflow are not incidental. Keeping converter modules and output devices on the base board away from the acquisition side reduces local heating of sensitive circuitry. The vertical board also presents an additional surface to the surrounding cabinet air while the rail footprint stays compact.
Assembly quality matters just as much. Controlled board angle keeps connectors seated without bending, maintains the designed spacing around the isolation barrier, and prevents mechanical stress from reaching solder joints. Insulation at external contact surfaces prevents a bracket or accessory from reducing clearance. Test pins provide defined access, but they also demand a repeatable fixture and careful handling so a probe cannot bridge separate domains.
A compact dual-board assembly is repeatable only when the production fixture controls the board relationship in three dimensions. The housing and rail clip must also hold the assembly securely during transport and field wiring. These mechanical choices protect the electrical design after the unit leaves the production line. They matter in panels exposed to vibration, repeated terminal tightening, or temperature cycling.
The 24 mm thin body mounts on standard 35 mm DIN rail, making the product suitable for modular panel layouts. When several channels are installed, the reduced rail allocation leaves more room for terminal blocks, separation between high- and low-voltage wiring, and future expansion. The benefit is especially clear in retrofit panels where enclosure dimensions and rail positions are already fixed.
The cabinet check should still include device depth, cable bend radius, ventilation, and terminal access. A compact outline that leaves no room for a screwdriver or a cable bend does not improve serviceability. The 24 mm profile is one part of a complete cabinet layout decision, not a substitute for one.
Compactness should also be evaluated with derating and maintenance in mind. A 24 mm product can reduce rail length, but its thermal performance still depends on neighboring heat sources, vertical airflow, enclosure temperature, and load. Mounting several units side by side without spacing is acceptable only when the panel thermal calculation supports it.
Confirm the rail allocation and depth for the complete channel count. Keep input and power wiring separated according to the panel EMC plan. Verify the DC 2 kV isolation boundary against the installation category, pollution condition, and enclosure design. Provide convection and enough terminal access for commissioning. Review the test-pin positions and insulated contact surfaces before service procedures are written. Finally, include the controlled assembly angle and board spacing in incoming inspection or supplier quality requirements.
The 90-degree dual-board architecture is not a cosmetic packaging trick. It gives input acquisition, signal processing, power conversion, and output functions defined physical zones. The 24 mm body reduces DIN-rail demand, while the DC 2 kV/1 min three-port isolation rating establishes a testable safety boundary. F2415S and F2405S supply modules, side-board test points, insulated contact surfaces, and controlled assembly angle support repeatability in production and service.
For cabinet layout review, provide the panel drawing, channel count, supply arrangement, signal type, and required isolation level. The right structural design is the one that preserves clearance, cooling, and service access after the enclosure door is closed.
