Siemens A5E31867280 LF2005-S/SP34 Replacement for SENTRON

Product Overview

Siemens A5E31867280 LF2005-S/SP34 Replacement for SENTRON: Seamless Transition & Legacy System Upgrade

When your existing SENTRON metering or protection panel relies on the Siemens A5E31867280 LF2005-S/SP34 Current Transformer (2000/5A) and the original unit reaches end-of-life, sourcing a verified drop-in replacement becomes the single most critical step in avoiding unplanned downtime. TOPNLMS maintains ready stock of this transformer to support both direct swap-outs and broader system modernization projects — from legacy SENTRON PAC metering panels to fully upgraded 7SJ or SIPROTEC protection relay architectures.

The LF2005-S/SP34 is a split-core, ring-type current transformer rated at 2000/5A, designed for integration into low-voltage switchgear, motor control centers (MCCs), and energy metering cabinets. Its compact SP34 window size and standardized secondary output of 5A make it directly compatible with a wide range of Siemens SENTRON PAC3200, PAC4200, and PAC5200 power monitoring devices, as well as third-party energy meters accepting 5A secondary input. When replacing a failed or aging unit, engineers can reuse existing secondary wiring, burden resistors, and terminal block layouts without panel redesign — a key advantage in retrofit scenarios where cabinet space and rewiring costs are tightly controlled.

In modernization projects migrating from older Siemens 3NJ or 3TK-series protection schemes to current SIPROTEC 5 or SENTRON 3WL/3VA circuit breaker platforms, the A5E31867280 serves as a stable metering anchor. Its 5VA burden rating and Class 0.5 accuracy ensure compatibility with both legacy analog instrumentation and modern digital protection relays. Engineers upgrading from discontinued 3UF motor management relays or older 7SJ602 overcurrent relays to the 7SJ85 or SIPROTEC 5 7SL87 line differential relay will find that the LF2005-S/SP34 secondary output integrates without recalibration, provided the relay’s CT input impedance is within the transformer’s rated burden.

For panel builders retrofitting existing switchgear with SENTRON 3VA molded-case circuit breakers or adding SENTRON PAC metering to an existing MCC, the SP34 window accommodates standard 3×240mm² cable bundles, eliminating the need to re-route primary conductors. This is particularly valuable in live-panel upgrades where primary circuit interruption must be minimized. The split-core design further reduces installation time compared to solid-core alternatives, supporting hot-swap procedures in facilities that cannot tolerate extended outages.

Compatibility Comparison Table

Seamless Upgrade Solutions

A current transformer replacement rarely occurs in isolation. In most SENTRON panel upgrades and MCC modernization projects, the LF2005-S/SP34 is installed alongside a broader set of components. Engineers migrating from legacy metering schemes typically pair this CT with a SENTRON PAC4200 power monitoring device, which accepts the 5A secondary directly and provides Modbus RTU and PROFIBUS DP communication to the plant SCADA. Where the existing panel uses a SENTRON 3WL air circuit breaker with an ETU45B or ETU55B trip unit, the LF2005-S/SP34 feeds the external metering circuit independently, preserving the breaker’s internal CT for protection functions.

Projects upgrading motor feeder protection from discontinued Siemens 3UF7 motor management relays to the current SIMOCODE pro V platform often retain the existing 2000/5A CT infrastructure, using the LF2005-S/SP34 as the primary current input to the new relay. Similarly, when replacing aging 7SJ602 overcurrent relays with SIPROTEC 5 7SJ85 units, the secondary wiring from the LF2005-S/SP34 connects directly to the relay’s CT input terminals without modification, provided the relay’s input burden is within the 5VA rating.

For complete panel refurbishment, the LF2005-S/SP34 is commonly installed with SENTRON 3VA2 molded-case circuit breakers for feeder protection, Siemens 8WH terminal blocks for secondary circuit termination, and SITOP PSU300S power supply modules for auxiliary power to the metering and relay equipment. In facilities requiring signal isolation between the CT secondary and the metering device — particularly in high-noise industrial environments — a Siemens 3RS17 signal conditioning module or equivalent transducer is inserted in the secondary loop. Where remote I/O expansion is needed, ET 200SP distributed I/O modules with analog input cards accept the conditioned 4–20mA signal derived from the CT secondary, feeding data upstream to a SIMATIC S7-1500 PLC for integrated energy management and process control.

Retrofit Guidance FAQ

Q: Can I reuse my existing secondary wiring when replacing with the A5E31867280?
A: Yes. The LF2005-S/SP34 uses standard 5A secondary terminals compatible with existing 2.5mm² or 4mm² secondary wiring. No rewiring is required in most direct replacement scenarios. Verify terminal polarity (S1/S2 markings) before energizing.

Q: Is the SP34 window size compatible with my existing primary cable bundle?
A: The SP34 aperture accommodates primary conductors up to 3×240mm² in standard configurations. For larger cable bundles or busbar installations, confirm the physical window dimensions against your panel layout before ordering.

Q: Will this CT work with my SENTRON PAC3200 or PAC4200 meter?
A: Yes. Both the PAC3200 and PAC4200 accept a 5A secondary input and are fully compatible with the LF2005-S/SP34. Configure the CT ratio as 2000/5 (or 400 as the ratio factor) in the meter’s parameter settings.

Q: Can I use this transformer with a SIPROTEC 5 protection relay?
A: Yes. SIPROTEC 5 relays (7SJ85, 7SL87, 7UT86, etc.) accept 5A CT inputs. Verify that the relay’s CT input burden does not exceed the transformer’s 5VA rating at maximum secondary current. Standard SIPROTEC 5 CT input impedance is well within this limit.

Q: What communication protocols are supported?
A: The LF2005-S/SP34 is a passive analog device with no onboard communication. Protocol support (Modbus RTU, PROFIBUS DP, IEC 61850, PROFINET) is determined by the connected metering or protection device. The CT’s 5A secondary output is protocol-agnostic and compatible with any device accepting a standard 5A CT input.

Q: How do I handle the CT secondary during installation or panel work?
A: Never open-circuit a CT secondary while the primary is energized. Always short-circuit the S1/S2 terminals using a dedicated CT shorting link before disconnecting the secondary circuit. Failure to do so will result in dangerously high secondary voltages.

Q: What is the lead time and shipping arrangement?
A: TOPNLMS ships from Xiamen, China. In-stock units are dispatched within 1–3 business days. International shipments via DHL Express, FedEx, or UPS typically arrive within 3–7 business days depending on destination. All units are tested and inspected prior to dispatch.

Warranty Assurance

Every Siemens A5E31867280 LF2005-S/SP34 supplied by TOPNLMS is covered by a 12-month warranty from the date of shipment. Prior to dispatch, each unit undergoes functional inspection including ratio verification, insulation resistance check, and visual inspection for physical integrity. Units that do not meet specification are quarantined and not shipped.

In the event of a warranty claim, TOPNLMS provides replacement or refund support within the warranty period. Our after-sales team responds to warranty inquiries within 1 business day. Replacement units are dispatched with priority shipping to minimize customer downtime. Warranty coverage applies to manufacturing defects and functional failures under normal operating conditions; it does not cover damage resulting from incorrect installation, open-circuit secondary operation, or electrical overstress beyond rated parameters.

For procurement teams requiring documentation, TOPNLMS can provide test reports, packing lists, and commercial invoices upon request. Bulk orders and long-term supply agreements are supported with dedicated account management and reserved stock arrangements.

To place an order or request a quotation, contact our team directly:

• Email: [email protected]
• Phone / WhatsApp: +86 18359293191
• Website: https://topnlms.com

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