Automated Test Systems with Repetitive Pulse Generators: Integration Guide for Production and R&D

Manual operation of a repetitive pulse generator suffices for occasional laboratory experiments, but routine testing—whether in production quality assurance or high-throughput R&D—demands automation. Automated RPG systems reduce operator error, increase test repeatability, and enable 24/7 accelerated aging campaigns. This article provides a practical guide to integrating repetitive pulse generators into automated test benches, covering software interfaces, hardware handshaking, safety system integration, and data management.

Why Automate Repetitive Pulse Testing?

Production environments face pressure to reduce test cycle time while maintaining quality. Manual RPG operation introduces variability: operators set slightly different voltages, forget to log parameters, or terminate tests early. Automation delivers:

• Consistency: Same pulse parameters every test, independent of shift or operator.

• Throughput: Automated sequencing allows testing multiple samples without human intervention.

• Data integrity: Automatic logging of voltage, current, PD activity, and pass/fail decisions to centralized database.

• Unattended operation: Overnight and weekend aging runs maximize equipment utilization (often reaching 300+ operating hours per week versus 40 hours with manual operation).

• Traceability: Complete audit trail for ISO 9001 and IATF 16949 compliance.

Communication Protocols and Interfaces

Modern repetitive pulse generators offer multiple remote control options. Selection depends on existing lab infrastructure and required data throughput:

Software Architecture for Automated RPG Systems

A typical automated repetitive pulse test system comprises three software layers:

Layer 1: Instrument Driver

Manufacturer-provided library (DLL, Python module, or LabVIEW driver) that handles low-level communication. Functions include set_voltage(), set_repetition_rate(), arm_output(), fire_pulse(), and read_status(). Verify that the driver supports your programming environment before purchasing.

Layer 2: Test Sequencer

Software that orchestrates test flow. Options range from simple Python scripts to commercial test executives (e.g., NI TestStand, Pyramid Technologies, or custom Node-RED flows). The sequencer must handle:

• Test parameter loading from CSV or database

• Conditional branching (e.g., if PD > threshold, reduce voltage and re-test)

• Timeout and exception handling

• Integration with other instruments (oscilloscopes, PD detectors, temperature chambers)

Layer 3: Data Management

Automatically log all test results to structured storage. Minimum required fields: timestamp, operator ID (or system ID for automated runs), test article serial number, RPG model and serial number, voltage, repetition rate, pulse width, rise time, test duration, number of pulses applied, pass/fail status, and raw measurement files (waveforms, PD patterns). Many labs use SQLite for local storage or PostgreSQL/InfluxDB for networked systems with web dashboards.

Hardware Integration and Signal Routing

Physical integration of an RPG into an automated test system requires careful design of signal paths:

• Trigger synchronization: Use a master clock or external trigger generator to coordinate RPG firing with oscilloscope acquisition and PD measurement. Fiber optic trigger links (e.g., 10 MHz reference over ST connectors) prevent ground loops and maintain sub-nanosecond jitter.

• Relay switching for multiple test articles: High-voltage relays (rated for RPG output voltage) allow sequential testing of multiple samples without operator intervention. Use vacuum or gas-filled relays with >10⁶ operation life. Include discharge resistors to bleed residual charge before switching.

• Safety interlock integration: Connect all enclosure doors, emergency stops, and ground verification sensors to the RPG's interlock input. The generator must automatically disable high-voltage output if any interlock opens. Use redundant contacts (two independent chains) for SIL 2 compliance.

• Thermal management in automated racks: Enclosing an RPG in a rack with other instruments reduces airflow. Monitor internal temperature via RPG's telemetry and automatically pause testing if temperature exceeds 45°C.

Programming Example: Python Automation

Python has become the dominant language for test automation due to its extensive library ecosystem. Example sequence for a 1000-hour aging test:

import pyvisa
import time
import sqlite3
from datetime import datetime

# Connect to RPG over Ethernet VISA
rm = pyvisa.ResourceManager()
rpg = rm.open_resource('TCPIP0::192.168.1.100::5025::SOCKET')
rpg.write('*RST')
rpg.write('VOLT 5000')  # 5 kV
rpg.write('FREQ 10000')  # 10 kHz
rpg.write('PWID 500')    # 500 ns
rpg.write('OUTP ON')

# Logging database setup
conn = sqlite3.connect('rpg_tests.db')
cursor = conn.cursor()
cursor.execute('''CREATE TABLE IF NOT EXISTS aging_log
                  (timestamp TEXT, voltage real, freq real, 
                   temperature real, pulse_count integer)''')

# Run aging for 1000 hours (3.6M seconds)
start_time = time.time()
while (time.time() - start_time) < 3600000:
    status = rpg.query('STAT:OPER?')
    temp = float(rpg.query('MEAS:TEMP?'))
    pcount = int(rpg.query('STAT:PULS:COUN?'))
    cursor.execute('INSERT INTO aging_log VALUES (?,?,?,?,?)',
                   (datetime.now().isoformat(), 5000, 10000, temp, pcount))
    conn.commit()
    time.sleep(300)  # Log every 5 minutes
    
rpg.write('OUTP OFF')
rpg.close()
conn.close()

Always include error handling and email alerts for anomalies in production automation scripts.

Integration with Partial Discharge Detection Systems

For insulation qualification, automated RPG testing often runs concurrently with PD measurement. Synchronization requirements:

• The RPG must provide a trigger output (e.g., TTL pulse at 10% of rising edge) to the PD detector.

• PD detector should measure phase-resolved PD (PRPD) patterns synchronized to each RPG pulse, not just average over time.

• Set automatic pass/fail: if PD magnitude exceeds 100 pC for more than 10 consecutive pulses, halt the test and flag the sample as failed.

• Some advanced RPGs integrate PD detection internally, simplifying automation by providing direct PD readback over the same control interface.

Production Line Integration Considerations

For manufacturing environments where the RPG is part of an inline test station:

• Cycle time optimization: Use parallel test fixtures: while one sample undergoes repetitive pulse testing, another is loaded/unloaded. Overlap RPG ramp-up and ramp-down times with operator handling.

• Barcode scanner integration: Automatically load test parameters based on product SKU scanned at entry.

• Pass/fail indicators: Connect RPG digital outputs (open collector or relay) to stack lights. Green for pass, red for fail, yellow for test in progress.

• Statistical process control (SPC): Automatically upload test results to SPC system. Monitor trends in PD inception voltage or leakage current across production batches to detect process drift before parts go out of spec.

• Operator safety: Light curtains or pressure-sensitive floor mats must be connected to RPG interlock. Test chamber doors should be interlocked such that opening during a test immediately removes high voltage and bleeds stored energy within 10 ms.

Common Automation Pitfalls and Solutions

Remote Monitoring and Alerts

For unattended automated runs (e.g., 1000-hour aging tests), implement remote monitoring:

• Configure the automation PC to send email or SMS alerts for test completion, failure, or equipment error.

• Create a web dashboard (using Grafana or Plotly Dash) showing real-time voltage, temperature, and PD trends accessible from any lab network computer.

• Set up watchdog timers: if automation software freezes, a hardware watchdog circuit (e.g., Arduino monitoring a software heartbeat) disables RPG output within 1 second.

Cost-Benefit of Automation

Automating a repetitive pulse generator involves initial development investment—typically 40–160 hours of engineering time for scripting and integration, plus $2,000–$10,000 for hardware (relays, interlocks, industrial PC). However, the return is substantial:

• Manual test: operator spends 8 hours per 24-hour test (setup, monitoring, logging, shutdown).

• Automated test: operator spends 0.5 hours for setup, plus occasional result review.

• For a lab running 50 aging tests annually (each 24 hours), automation saves 375 operator hours per year—equivalent to 9 weeks of engineering time.

For production environments testing 10,000 units annually at 5 minutes per unit, automation saves 800+ operator hours per year and eliminates human error in pass/fail decisions.

Automated integration transforms a repetitive pulse generator from a manually operated instrument into a high-throughput, 24/7 test asset. With modern software tools and robust safety interlocks, even small labs can achieve production-grade automation that improves data quality, reduces costs, and accelerates product qualification cycles.