The IS2020RKPSG2A is a VME rack power supply designed for the Mark* VI gas turbine control system, representing a newer generation of power module design. This unit is mounted on the side of the VME control and interface rack and is responsible for providing multiple DC output voltages to the entire VME backplane and external devices. These outputs include +5V, ±12V, ±15V, and ±28V, with an optional +335V DC output for powering TRPG flame detectors. The IS2020RKPSG2 supports a 125V DC input, delivers a total output power of 400W, and is suitable for high-reliability, redundant industrial control environments.
2. Key Features & Functions
2.1 Multiple Voltage Outputs
The IS2020RKPSG2A provides multiple independent output voltages to meet the power requirements of the VME backplane and various interface modules:
+5V: Primarily used for digital logic circuits, such as the VME controller, VCMI, VDSK, and other core modules.
±12V & ±15V: Commonly used for analog circuits, operational amplifiers, communication interfaces, etc.
±28V: Used for driving relays, sensors, or external actuators.
+335V (Optional): Dedicated for high-voltage equipment like flame detectors.
2.2 Dual Input Voltage Compatibility
The power supply supports two input voltage modes:
125V DC Input: Typically sourced from a Power Distribution Module (PDM), suitable for high-voltage DC systems in industrial settings.
24V DC Input: Suitable for low-voltage control systems or backup power scenarios. (Note: The IS2020RKPSG2 model specifically uses the 125V input; the 24V input is for the LVPSG series).
2.3 Status Monitoring & Identification
The IS2020RKPSG2A features comprehensive status indication and identification functions:
Tri-Color LED Indicators:
Status Output Signal: Provides a passive dry contact signal via a solid-state relay, mirroring the status of the green LED, enabling system-level monitoring.
ID Output: Utilizes a Dallas DS2502 chip to output identity information such as serial number, manufacturing date, and model number, facilitating system identification and management.
2.4 Support for Redundant Operation
The IS2020RKPSG2A is designed to support redundant power supply configurations, enabling fault tolerance and improved system reliability in parallel operation scenarios.
3. Working Principle & Internal Structure
3.1 Power Supply Architecture
The IS2020RKPSG2A employs a modular design, primarily consisting of the following sections:
Input Filtering & Protection Circuit: Filters the input DC voltage and provides surge protection, over-voltage, and under-voltage protection.
DC-DC Conversion Modules: Convert the input voltage to the required multiple output voltages.
Output Distribution & Protection Circuitry: Each output channel is equipped with over-current, over-voltage, and short-circuit protection.
Control Logic & Status Management: Manages power enable/disable, fault detection, status output, and ID recognition.
3.2 Output Voltage Distribution
The top of the power supply features two connectors, PSA and PSB, which deliver power to the VME backplane. The bottom hosts multiple output interfaces, including:
PS28A~E: Five +28V outputs, each corresponding to a different section (A through E) of the VME rack.
PS335: Optional +335V output connector.
PSSTAT: Status output connector.
PS125: Input power connector for 125V DC.
3.3 Protection Mechanisms
The IS2020RKPSG2A incorporates multiple protection features:
Input Under-Voltage/Over-Voltage Protection: Prevents the power supply from operating outside the specified input voltage range.
Output Over-Current/Short-Circuit Protection: Most outputs feature self-recovery functionality after the fault is cleared (except +5V, which may latch).
Output Over-Voltage Protection: If an output voltage exceeds its set threshold, that output is latched off and requires a reset to recover.
Over-Temperature Protection: Monitors the temperature of key power modules and shuts down the affected output in case of overheating.
4. Installation & Wiring
4.1 Mechanical Installation
The power supply is mounted to a metal bracket on the right-hand side of the VME rack. Installation steps include:
Aligning the power supply module with the bracket and securing it with four screws.
Sliding the assembled module and bracket into the rack and connecting the four rear-side connectors.
Installing the top PSA/PSB connector bracket assembly and tightening the captive fastener.
Connecting the bottom input and output power connectors.
4.2 External Device Power Configuration
The PS28C output can be used to power external peripheral devices. To enable this, the jumper plug located on the bracket to the left of the rack must be moved from the "Normal" position to the "Isolated" position, providing electrical isolation from the VME backplane.
5. Operation & Status Indication
5.1 Power Switch
The front panel features a locking-type power switch used to enable or disable all output voltages. In a fault state, toggling the switch can serve as a reset function.
5.2 LED Status Explanation
Yellow LED ON: Input power is present, but outputs are disabled.
Green LED ON: All outputs are functioning normally, no faults detected.
Red LED ON: A fault has been detected. Requires investigation of input or output conditions.
5.3 Fault Handling
The power supply manages three general classes of faults:
Transient Faults: Such as over-current protection, where the output recovers automatically once the fault condition is removed.
Reset-Required Faults: Such as over-voltage protection, which require a switch cycle or removal of input power to reset.
Permanent Faults: Require replacement of the power supply module.
6. Diagnostics & Maintenance
6.1 Fault Diagnosis
The system can diagnose issues using the power supply's status output, ID signal, and front panel LEDs:
No LEDs Illuminated: Indicates a missing input power or a defective power supply unit.
Red LED Constantly ON: Suggests a potential input abnormality, output over-voltage/under-voltage, or over-temperature condition.
Green LED ON but Voltage Abnormal: May indicate a localized short circuit or excessive load on a specific output.
6.2 Maintenance Recommendations
The power supply module contains no field-serviceable components. If faulty, the entire unit must be replaced.
Before replacement, ensure power is turned OFF and verify the absence of hazardous voltage.
After installation, check that all connectors are secure and grounding is reliable.
