ABB RTXP18 RK926015-BH Dead Machine Test Switch – COMBIFLEX

ABB RTXP18 RK926015-BH: 18-Pole COMBIFLEX Dead Machine Test Switch in Protection Relay Architectures

In high-voltage substation protection schemes, the ability to isolate, test, and re-commission a relay without interrupting the primary circuit is not a convenience — it is a fundamental operational requirement. The ABB RTXP18 RK926015-BH is an 18-pole dead machine test switch engineered for exactly this function within the ABB COMBIFLEX and MODULEX relay system families. It provides a mechanically keyed, electrically rated interface between the relay element and the secondary wiring harness, enabling secondary injection testing, relay withdrawal, and circuit continuity verification under live substation conditions.

The suffix RK926015-BH designates a specific internal contact wiring topology — not a cosmetic variant. Each suffix maps to a defined terminal-to-contact matrix that must correspond precisely to the protection scheme drawing. Substituting an incorrect suffix introduces the risk of CT secondary open-circuit or VT short-circuit during testing, both of which carry serious equipment and personnel safety implications. This is a component where OEM sourcing is not optional.

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Technical Parameters

Hardware Logical Analysis

The RTXP18 operates on a make-before-break contact sequencing principle during relay withdrawal. As the relay element is extracted from the COMBIFLEX case, the test switch contacts close the CT secondary circuits before the relay’s own CT input terminals open. This sequencing is not incidental — it is a deliberate hardware interlock that prevents CT secondary open-circuit, which would otherwise generate dangerous overvoltage transients capable of damaging insulation and injuring personnel.

The 18-pole contact matrix is arranged in a defined functional grouping: CT secondary shorting contacts occupy the first contact tier, VT secondary isolation contacts occupy the second tier, and trip/alarm output bridging contacts occupy the third tier. The RK926015-BH suffix specifies the exact wiring of these tiers to the terminal block, which must match the protection scheme’s secondary wiring diagram. This is not a generic relay socket — it is a precision-wired circuit element.

EMC and contact integrity: The silver-alloy contact surfaces with gold flash plating maintain stable contact resistance below 5 mΩ across the rated temperature range. In substation environments where secondary wiring runs alongside high-voltage busbars, the low-resistance contact path ensures that injected test currents reach the relay element without voltage drop artifacts that could distort test results. The housing material provides adequate shielding against capacitively coupled interference from adjacent HV equipment.

Mechanical keying and polarization: The 18-pole connector is mechanically polarized to prevent 180° inversion insertion — a failure mode that would reverse CT polarity and cause differential protection to operate incorrectly on load current. The keying geometry is specific to the COMBIFLEX 18-pole case and is not interchangeable with RTXP8 or RTXP24 variants without a mechanical adapter, which itself requires engineering review.

System Integration Benefits

• CT secondary continuity during relay withdrawal: Make-before-break contact sequencing eliminates CT open-circuit risk, allowing relay removal from energized panels without primary circuit interruption.
• Secondary injection testing without primary outage: Test current can be injected directly through the RTXP18 interface while the primary circuit remains live, reducing maintenance window requirements.
• Deterministic contact resistance: Silver-alloy contacts maintain <5 mΩ resistance, ensuring injected test signals are not attenuated or distorted before reaching the relay element.
• Suffix-coded wiring traceability: The RK926015-BH suffix provides a documented, auditable link between the physical hardware and the protection scheme drawing, supporting IEC 61511 functional safety documentation requirements.
• Polarized insertion prevents wiring errors: Mechanical keying eliminates the possibility of reversed CT polarity during relay reinsertion — a failure mode that would cause differential protection misoperation on load current.
• Compatibility with automated test systems: The RTXP18 interface is compatible with Omicron CMC and FREJA relay test sets via standard COMBIFLEX test plugs, enabling automated secondary injection without custom wiring adapters.
• Reduced commissioning time: Standardized COMBIFLEX interface eliminates per-panel wiring adaptation, allowing relay test routines to be executed from a single test procedure document across all panels using the same relay type.
• Long-term spare parts availability: ABB COMBIFLEX components have a documented multi-decade service history in utility substations. The RTXP18 remains in production and is supported by ABB’s global spare parts network, reducing obsolescence risk for long-lifecycle substation assets.

Quality Assurance & Global Logistics

Every ABB RTXP18 RK926015-BH unit dispatched from our Xiamen facility undergoes a structured pre-shipment verification process. Visual inspection confirms label integrity, suffix code accuracy, and absence of contact contamination or mechanical damage. Functional verification checks contact continuity across all 18 poles and insulation resistance between adjacent contact tiers. Units that do not meet these criteria are quarantined and not shipped.

Packaging uses anti-static foam-lined cases with moisture-barrier outer packaging. For international shipments, each unit is accompanied by a commercial invoice, packing list, and certificate of conformity. Country-of-origin documentation (Sweden) is available on request for customs clearance in markets with preferential tariff agreements.

Logistics: In-stock orders are dispatched within 24–48 hours via DHL Express or FedEx International Priority from Xiamen Gaoqi International Airport. Transit times to major industrial hubs: Europe 3–5 days, North America 4–6 days, Southeast Asia 2–3 days, Middle East 4–5 days. For urgent maintenance requirements, same-day dispatch is available on confirmed orders received before 14:00 CST. Tracking numbers are provided within 2 hours of dispatch.

Bulk procurement (>10 units) and project-based orders are supported with formal quotation, lead time commitment, and consolidated shipping documentation. Contact our team for framework agreement pricing on recurring maintenance contracts.

Contact Information

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