VAX 9000 Family Power System Technical Description

This document, "VAX 9000 Family Power System Technical Description" (Order Number EK-KA90P-TD-001), provides a detailed overview and functional description of the VAX 9000 family's power system, primarily focusing on Model 210 systems. It is intended for Customer Services personnel and as a training resource.

The VAX 9000 power system is a complex, high-power system that converts AC input power into a regulated 280 Vdc, which is then stepped down to various low voltage DC levels required by the system's logic units. It incorporates extensive monitoring, control, and diagnostic capabilities.

Key aspects of the power system described include:

• Power Front Ends (PFEs):

  • H7390-A Power Front End (PFE): Converts 3-phase 208 Vac to 280 Vdc, capable of powering an 18.5 kW load, and provides EMI suppression and ride-through capability (for brief power interruptions).
  • H7392 Utility Port Conditioner (UPC): Converts 3-phase AC input (various voltages) to a regulated 280 Vdc, capable of powering a 20 kW load, with ride-through capability. The UPC serves as an optional or standard front end depending on the system model and region.

• Power Distribution: Details high voltage (280 Vdc) and low voltage DC distribution across various cabinets (IOA, CPU, SCU) and components.

• Converter Groups: Describes different types of DC/DC converters (H7380, H7214, H7215) that step down 280 Vdc to specific low voltages (e.g., +5V, -5.2V, -3.4V, ±12V) for CPU, SCU, XMI, and Service Processor Unit (SPU) components. Some converters (H7380) support N+1 redundancy for Model 400 systems and current sharing.

• Monitoring and Control Subsystem:

  • Regulator Intelligence Cards (RICs - H7388 CPU RIC, H7389 I/O RIC): Microprocessor-controlled boards that turn power converters on/off, monitor their voltage output and environmental conditions (temperature, overcurrent), and report status/errors.
  • Power and Environmental Monitor (PEM): An 8031 microprocessor-based module acting as a central interface between the power system, RICs, and the SPU. It polls RICs, manages the Operator Control Panel (OCP), handles Battery Backup Units (BBUs), and relays error information.
  • Signal Interface Panel (SIP): Provides critical communication links and control signals among the PEM, RICs, OCP, BBUs, and power front ends, also generating power system clocks.
  • H7386 Overvoltage Protection (OVP) Module: Monitors critical DC voltage buses and triggers protective shutdown mechanisms (e.g., SCR shorting) in case of overvoltage.

• Cooling System: Details the air movers (blowers) and various temperature and airflow sensors used to maintain optimal operating temperatures within the cabinets.

• Power Control Subsystem (PCS) Communication: Explains the communication protocols (XXNET) and message formats used between the SPU, PEM, and RICs for command/reply sequences and exception reporting.
• Initialization and Diagnostics: Covers the power-up sequences and built-in self-tests (BISTs), including hard-core and invokable diagnostics for both PEM and RICs, and how system status and errors are communicated via LEDs and OCP codes.

The document provides extensive tables and block diagrams to illustrate physical layouts, electrical specifications, signal paths, and operational logic for various components.