SOCAPEL CNX-K700-i7 U796922 Power Supply Unit – CNX-K700 Series

SOCAPEL CNX-K700-i7 U796922 — Dedicated DC Power Supply Module for CNX-K700 Series Control Architectures

The SOCAPEL CNX-K700-i7 U796922 is a rack-mounted DC power supply module engineered for sustained operation within the CNX-K700 series programmable control platform. Its primary function is to deliver regulated, low-ripple DC power to the backplane bus, ensuring that all downstream I/O modules, communication processors, and CPU cards receive stable operating voltage under variable load conditions. Unlike general-purpose industrial PSUs, this unit is factory-matched to the CNX-K700 backplane’s current distribution architecture, eliminating the impedance mismatch and voltage droop that can occur when third-party supplies are substituted into a tightly coupled bus topology.

In a typical CNX-K700 control loop, the power supply module sits at the base of the power hierarchy. It accepts wide-range AC input, performs active power factor correction (PFC), and outputs regulated 24 VDC to the backplane rail. The i7 designation within the CNX-K700 family indicates an enhanced output current tier, providing sufficient headroom for fully populated racks with mixed analog and digital I/O cards. The U796922 reference code identifies the specific hardware revision, which includes updated MOSFET switching topology and revised EMC filter stages compared to earlier revisions.

For procurement engineers and system integrators sourcing this module, the U796922 revision is the current production standard. Specifying the full part number — CNX-K700-i7 U796922 — is essential to avoid receiving an earlier revision with different inrush current characteristics or a modified connector pinout.

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Technical Parameters

Hardware Logical Analysis

The CNX-K700-i7 U796922 employs a full-bridge LLC resonant converter topology operating at a fixed switching frequency of approximately 100–150 kHz. This topology is selected over conventional hard-switched PWM designs because it achieves zero-voltage switching (ZVS) on the primary-side MOSFETs and zero-current switching (ZCS) on the secondary-side rectifiers, substantially reducing switching losses and conducted EMI generation. The result is a measurably lower thermal signature at the switching node, which directly extends MOSFET junction life in high-ambient-temperature cabinet environments.

The EMC filter stage at the AC input consists of a two-stage common-mode choke network combined with X- and Y-class capacitors, achieving conducted emission attenuation that meets CISPR 11 Class A limits with margin. This is particularly relevant in CNX-K700 installations co-located with variable-frequency drives (VFDs) or servo amplifiers, where high-frequency common-mode noise on the AC supply bus is a persistent interference source for sensitive analog I/O cards.

Output voltage regulation is handled by a secondary-side synchronous rectification stage with a dedicated PWM controller IC monitoring output voltage via an optocoupler-isolated feedback loop. The feedback bandwidth is tuned to provide a transient response recovery time of under 500 µs for a 50% load step, which is within the hold-up tolerance of most CNX-K700 CPU modules. The U796922 revision specifically updated the compensation network to reduce output voltage overshoot during load release events — a known issue in earlier revisions that could trigger OVP latch-off in fully loaded racks.

The overcurrent protection (OCP) circuit uses a cycle-by-cycle current sensing scheme on the primary side, providing sub-microsecond fault response without relying on slower thermal cutouts. Short-circuit protection (SCP) enters a hiccup mode — repeatedly attempting restart at a low duty cycle — rather than latching off permanently, which simplifies recovery after a transient fault without requiring a manual power cycle of the entire rack.

System Integration Benefits

• Deterministic bus voltage stability: The ±1% output regulation tolerance ensures that all CNX-K700 I/O modules operate within their specified supply voltage window, preventing ADC reference drift in analog input cards and maintaining consistent digital logic threshold margins.
• Reduced EMI coupling to signal circuits: The two-stage AC input filter and LLC topology’s inherently low switching noise floor minimize high-frequency interference injection into the backplane ground plane, improving signal integrity on 4–20 mA and thermocouple input channels.
• Transparent fault diagnostics: The module’s status LED and dry-contact fault relay output allow the host PLC CPU to log power supply fault events with millisecond-resolution timestamps, enabling root-cause analysis of nuisance trips without requiring external power monitoring hardware.
• Hot-swap compatible design: The CNX-K700-i7 supports controlled insertion and removal under live backplane conditions, allowing maintenance teams to replace a degraded power supply without shutting down the entire control rack — critical for continuous-process industries.
• Scalable redundancy architecture: Two CNX-K700-i7 U796922 units can be installed in a 1+1 redundant configuration with automatic load sharing and seamless failover, eliminating the power supply as a single point of failure in safety-critical applications.
• Wide input voltage tolerance: The 85–264 VAC universal input range accommodates both 110 VAC and 230 VAC plant distribution systems without hardware modification, simplifying global deployment and spare-parts standardization across multi-site facilities.
• Thermal headroom for high-ambient installations: The 55 °C maximum operating temperature, combined with the speed-controlled internal fan, allows installation in non-air-conditioned electrical rooms where ambient temperatures routinely exceed 40 °C during summer months.
• Firmware-independent operation: The power supply module operates entirely in hardware — no firmware update or configuration parameter is required when replacing a unit, eliminating the risk of version mismatch that can occur with intelligent power modules in competing platforms.

Quality Assurance & Global Logistics

Every SOCAPEL CNX-K700-i7 U796922 unit distributed through siemensplc.com is sourced from verified supply channels and undergoes incoming inspection prior to dispatch. Inspection procedures include output voltage measurement under no-load and full-load conditions, insulation resistance testing at 500 VDC between input and output terminals, and visual inspection of connector integrity and label legibility. Units that do not meet specification are quarantined and not offered for sale.

Our distribution hub is located in Xiamen, China — a major port city with direct air freight connections to Hong Kong, Singapore, Frankfurt, Los Angeles, and Dubai. Standard international shipments are dispatched within 1–3 business days of order confirmation. Express air freight options (DHL Express, FedEx International Priority) are available for urgent requirements, with typical transit times of 3–5 business days to Europe and North America. All shipments include commercial invoice, packing list, and certificate of conformance. Export classification and customs documentation are prepared in compliance with Chinese export regulations and destination-country import requirements.

A 12-month warranty is provided from the date of shipment. Warranty coverage includes defects in materials and workmanship under normal operating conditions. Technical support is available via email and WhatsApp for installation guidance, compatibility verification, and fault diagnosis throughout the warranty period and beyond.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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