The **SBS-22-R** is a specific model within the **SBS Series** of high-power, industrial-grade **Static Transfer Switches (STS)**. These devices are designed to provide instantaneous switching between two independent AC power sources to ensure uninterruptible power for sensitive electronic equipment. --- ### 1. Core Technical Specifications The "22" typically refers to the amperage rating (in this case, often 20A or 22A depending on the regional configuration) and "R" signifies a **Rack-mount** form factor. | Feature | Specification | | :--- | :--- | | **Input Channels** | Dual AC Inputs (Source A & Source B) | | **Switching Time** | < 4ms to 8ms (Typical) | | **Form Factor** | 1U or 2U 19-inch Rack-mount | | **Voltage** | 110V/120V or 208V/230V (Model dependent) | | **Communication** | SNMP, RS232, or Dry Contacts | --- ### 2. Key Electronic Components The internal architecture of the SBS-22-R consists of several critical electronic subsystems: #### A. Silicon Controlled Rectifiers (SCRs) The "Static" in Static Transfer Switch comes from the use of **SCRs** instead of mechanical relays. * **Function:** They act as high-speed solid-state switches. * **Advantage:** Unlike mechanical relays that take 20-50ms to switch, SCRs can transfer the load in less than a quarter of a cycle, preventing equipment reboots. #### B. Control Logic & Microprocessor This is the "brain" of the unit. * **Voltage Monitoring:** Constantly samples the waveform of both input sources. * **Phase Synchronization:** Ensures that the switch only occurs when the two sources are in-phase (or handles the transition safely if they are out of phase). * **Decision Making:** If Source A drops below a predefined threshold (e.g., -15%), the logic triggers the SCRs to pull from Source B. #### C. Sensing and Filtering Circuitry * **Isolation Transformers:** Used in some variants to protect internal logic from power surges. * **EMI/RFI Filters:** Clean up electrical noise from the input lines before it reaches the connected load. --- ### 3. Functional Logic Diagram ```mermaid graph LR A[Source A - Primary] --> S1{SCR Switch 1} B[Source B - Backup] --> S2{SCR Switch 2} S1 --> L[Critical Load] S2 --> L Logic[Microprocessor] -. Monitor .- A Logic -. Monitor .- B Logic -. Control .- S1 Logic -. Control .- S2 ``` --- ### 4. Operational Indicators The SBS-22-R usually features an electronic front panel containing: 1. **LED Matrix:** Displays which source is currently active. 2. **Alarm Buzzer:** Triggered during source failure or internal fault. 3. **Manual Override:** Electronic buttons to force a transfer for maintenance.