Siemens 7SS5215-5CA00-1AA1 7SS52 Bay Control Unit

Module Feature

7SS5215-5CA00-1AA1 belongs to Siemens SIPROTEC 7SS52 series bay control unit for busbar protection system.

It is a modular I/O and logic processing unit for each switchgear bay, cooperating with central busbar protection main device. It collects breaker status, CT signals, isolator and earthing switch binary signals, executes bay interlock logic, breaker failure detection and trip output. Rated auxiliary power range 48…250V DC, multiple configurable binary inputs and relay outputs. Conformal coated PCB, strong anti-interference capability, meets substation EMC requirements. This model is discontinued, widely stocked as maintenance spare for power utility and industrial plant busbar protection cabinet.

Working principle

The bay unit receives current signals and equipment status contacts from local bay.

It executes breaker failure detection logic: after protection trip command is issued, if fault current still exists after preset delay, it sends re-trip and remote trip signal to adjacent breakers. It transmits bay data to central busbar protection device via dedicated communication link, receives trip command and drives output relays to open local circuit breaker. Continuous internal self-check monitors power supply, communication link and output circuit health status.

Onboard components

Signal conditioning board, protection logic CPU, binary input circuit, relay output contact group, bay communication interface module, fault detection circuit, status LED array, terminal block and coated PCB with metal front panel.

LED indicators

Green LED: module running healthy Yellow LED: trip command / bay active Red LED: hardware fault or protection alarm

Hardware self‑diagnosis

Built-in supervision detects power supply anomaly, communication interruption, binary channel fault and relay circuit abnormality. Configuration and fault diagnosis are completed by Siemens DIGSI 4 / DIGSI 5 software.

Programming softwareDIGSI 4 / DIGSI 5, used for bay logic configuration, breaker failure time setting, I/O assignment, communication parameter setup and fault record download.

Electrical & Process Parameters

Model:7SS5215-5CA00-1AA1 Brand:Siemens Device type:7SS52 busbar protection bay unit Function:Bay signal acquisition, interlock logic and breaker failure protection for busbar protection system

Mechanical & Structure

Mounting:1/3 19 inch rack plug-in installation Protection class:IP20 Housing:Metal front panel + coated PCB

Environmental

Operating temperature:-5℃ ~ +55℃ Storage temperature:-40℃ ~ +85℃ Ambient humidity:5~95% non‑condensing

Certification:CE, IEC60255, substation EMC Status:Discontinued original Siemens bay unit spare

Installation

Isolate protection cabinet auxiliary power and lock related bay before replacement. Check backplane communication connector, confirm binary input and trip output wiring, download bay configuration, test breaker failure logic and trip output action after commissioning.

Interface

Backplane bus communication connector, binary input terminal, trip relay output terminal, auxiliary DC power terminal.

Diagnostic

Offline alarm: Backplane contact poor, communication link broken. Breaker failure false alarm: Current circuit wiring error, setting curve mismatch. No trip output: Relay contact burnout, interlock blocking.

Product Brief7SS5215-5CA00-1AA1 unit, Siemens 7SS52 bay unit spare for high and medium voltage busbar protection and breaker failure protection cabinet replacement.