ABB SPAJ 135 C-AA Maintenance-Ready Spare for SPAJ Automation

ABB SPAJ 135 C-AA Maintenance-Ready Spare for SPAJ Automation

The ABB SPAJ 135 C-AA is a combined overcurrent and earth-fault protection relay engineered for demanding industrial power distribution and motor protection applications. As a maintenance-ready original spare, it is designed to support rapid field replacement, minimize unplanned downtime, and extend the operational life of legacy ABB SPAJ Series protection systems. Whether you are managing a scheduled outage, responding to a protection trip event, or building a strategic spare parts inventory for a critical substation or motor control center, the SPAJ 135 C-AA delivers the reliability and compatibility that maintenance and procurement engineers depend on.

Sourced directly from verified ABB supply channels, each unit undergoes functional testing prior to shipment and is backed by a 12-month warranty. This ensures that when a replacement is needed — whether during a planned turnaround or an emergency shutdown — the spare is ready to install without additional qualification delays.

Spare Maintenance Table

Maintenance Planning for Continuous Operation

When replacing the SPAJ 135 C-AA in the field, a thorough inspection of the surrounding protection circuit is essential to ensure system integrity and prevent repeat failures. Maintenance engineers should treat this replacement as an opportunity to audit the entire protection loop.

Begin with the current transformer (CT) secondary wiring — verify that CT shorting links are correctly managed during relay removal and that secondary burden is within specification for the new relay. Inspect the auxiliary power supply module feeding the relay panel; ABB SDCS or equivalent DC/DC converters in the same cubicle should be checked for output voltage stability and ripple, as a degraded supply is a common root cause of nuisance trips or relay malfunction.

Check all output relay contacts and trip circuit wiring connected to the SPAJ 135 C-AA. Contacts on the trip relay board — including those driving circuit breaker shunt trips and alarm annunciators — should be tested for continuity and contact resistance. If the panel includes an ABB SPTO or SPTU trip output relay module, inspect it in parallel with the SPAJ replacement, as these components share the same operational duty cycle.

For panels with SPACOM communication modules or SPA-bus serial interfaces, verify that the relay address settings and baud rate configuration are correctly transferred to the replacement unit. Communication faults following a relay swap are frequently caused by address conflicts or incorrect DIP switch settings on the new module.

Inspect terminal blocks and wiring ferrules in the relay panel. Loose or corroded terminals on the CT input, voltage input, and binary output circuits are a leading cause of intermittent protection failures in aging installations. Replace any suspect terminals using DIN-rail mounted screw or spring-clamp terminal blocks rated for the application.

If the installation includes signal isolators or transducers on the measurement inputs — such as 4–20 mA current loop isolators feeding SCADA or DCS systems — verify their calibration and output signal integrity after the relay replacement. Similarly, check any surge protection devices (SPDs) installed on the CT and VT secondary circuits, as these may have absorbed fault energy during the event that caused the original relay failure.

For sites running ABB REF615 or REF630 feeder protection IEDs alongside legacy SPAJ relays in a hybrid protection scheme, confirm that the protection coordination settings remain consistent after the SPAJ 135 C-AA is replaced. Time-current coordination between the SPAJ overcurrent stage and upstream IED protection zones should be re-verified using the site’s protection coordination study.

Finally, review the panel fusing and miniature circuit breakers (MCBs) protecting the auxiliary supply to the relay. A blown fuse or tripped MCB on the auxiliary circuit is sometimes misdiagnosed as relay failure; replacing the SPAJ without restoring the auxiliary supply will result in immediate repeat failure.

Site Replacement Workflow

Step 1 — Isolation and permit: Obtain a safe work permit and isolate the feeder or motor circuit protected by the SPAJ 135 C-AA. Confirm that the circuit breaker is open and locked out before proceeding.

Step 2 — CT secondary shorting: Short the CT secondary terminals before disconnecting the relay to prevent open-circuit CT hazards. Use approved CT shorting plugs or links.

Step 3 — Record settings: Document all existing protection settings — overcurrent pickup, time multiplier, earth-fault threshold, and high-set values — from the relay front panel or from the site protection setting schedule before removal.

Step 4 — Remove and inspect: Remove the SPAJ 135 C-AA from its panel mounting. Inspect the relay case, terminal connections, and rear connector for signs of overheating, arcing, or moisture ingress. Photograph the wiring before disconnection.

Step 5 — Install replacement: Mount the new SPAJ 135 C-AA, reconnect all wiring per the original scheme, and remove CT shorting links. Verify auxiliary supply polarity and voltage level before energizing the relay.

Step 6 — Setting transfer and commissioning: Enter all protection settings from the recorded schedule. Perform a secondary injection test to verify overcurrent and earth-fault pickup and timing. Confirm output relay operation by simulating a trip condition.

Step 7 — Return to service: Close the circuit breaker, confirm relay is in service mode, and update the maintenance log with the replacement date, new relay serial number, and test results.

This workflow ensures that the replacement SPAJ 135 C-AA is fully commissioned before the protected circuit is returned to service, eliminating the risk of an undetected protection failure on the first post-maintenance fault.

Spare Parts Support FAQ

Q1: Is the SPAJ 135 C-AA a direct drop-in replacement for other SPAJ Series relays?
The SPAJ 135 C-AA is a direct mechanical and electrical replacement for other SPAJ 135 variants within the ABB SPAJ Series. It shares the same panel cutout dimensions, terminal layout, and auxiliary supply range as the SPAJ Series platform. However, protection function configuration (overcurrent/earth-fault combination) and setting ranges should be verified against the site protection coordination study before installation. For sites using SPAJ 110, SPAJ 120, or SPAJ 140 variants, confirm that the protection function set of the 135 C-AA matches the application requirements.

Q2: What pre-shipment testing is performed on each unit?
Every SPAJ 135 C-AA unit is functionally tested prior to shipment. Testing covers auxiliary power supply energization, LED and display functionality, output relay contact operation, and basic overcurrent pickup verification. Units that do not pass functional testing are not shipped. A 12-month warranty is provided from the date of shipment, covering manufacturing defects and functional failures under normal operating conditions.

Q3: How should the SPAJ 135 C-AA be stored as a long-term spare?
For long-term spare storage, keep the relay in its original packaging in a dry, temperature-controlled environment (0°C to +40°C, relative humidity below 75% non-condensing). Avoid storage near strong magnetic fields or sources of vibration. Inspect the unit annually for signs of moisture ingress or physical damage. For critical installations, consider maintaining at least one SPAJ 135 C-AA on-site as a hot spare to support same-shift replacement in the event of an unplanned protection trip.

Q4: Can long-term supply of the SPAJ 135 C-AA be guaranteed for aging installations?
Yes. We maintain dedicated inventory of SPAJ Series protection relays to support legacy ABB protection systems that remain in service beyond the original product lifecycle. For sites with multiple SPAJ relay panels, we recommend a site-wide spare parts audit to identify all SPAJ variants in use and establish a consolidated spare parts holding. Contact our team to discuss volume pricing, reserved stock agreements, and lead time commitments for multi-unit orders.

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