DS4815CHGB | GE Factory Tested & ISO Certified

Description

Product Introduction

The “B” revision takes the brute-force capability of the CHGA and adds some brains. Same 5-amp output, same voltage options (24/48/125VDC), but with a smarter protection scheme. The CHGB adds per-channel temperature sensing to the existing current monitoring—the board now knows not just how much current is flowing, but also how hot each MOSFET is getting. This lets the CPU implement predictive thermal management: reduce PWM duty cycle or pre-trip before a channel overheats. The upgrade came from field feedback—plants in hot environments were seeing thermal shutdowns that could have been prevented.

Compared to the DS4815CHGA, the “B” revision swaps the MOSFETs for a next-gen part with lower on-resistance (0.035Ω vs. 0.05Ω) and adds a dedicated thermal sensor on each output driver. The terminal assignment stayed identical—it’s a direct drop-in. The current sense accuracy improved to ±3% (from ±5%), which matters for sensitive load monitoring. The board also adds a hardware revision ID that the CPU can read, so the firmware can automatically adjust protection thresholds. Requires Mark V CPU firmware v5.5 or higher.

Key Technical Specifications

Compatible Replacement Models

Frequently Asked Questions (FAQ)

Q: What’s the difference between CHGA and CHGB—and why should I care?
Thermal management. The CHGA measured current and voltage; the CHGB adds a temperature sensor on each MOSFET. That means if a channel is running hot (say, 75°C) but not yet overcurrent, the CPU can reduce the output’s PWM duty cycle or send a warning before the channel hits 85°C and shuts down. In practice, this prevents nuisance trips in high-ambient cabinets. We’ve seen CHGA boards trip at 55°C ambient with 8 channels at 4A; the CHGB can warn at 70°C and stay online by reducing duty cycle.

Q: Can the CHGB communicate the thermal data to the Mark V CPU?
Yes—if your CPU firmware is v5.5 or higher. The thermal data appears as additional diagnostic channels in the I/O map (16 new channels—8 for current, 8 for temperature). The CPU can log the temperature trends, which is useful for predictive maintenance. If your firmware is older, the board will work but the thermal data won’t be visible—you’ll just get the same functionality as the CHGA.

Q: The temperature on channel 2 shows 90°C in the Toolbox, but the output is only at 3A. Is that normal?
Possibly. The MOSFET temperature depends on (1) the output current, (2) the ambient temperature, and (3) the airflow. At 3A and 55°C ambient, 90°C die temperature is within spec—the MOSFETs are rated for 150°C junction temperature, but the board trips at 85°C case temperature. If you’re seeing 90°C, the channel is near the trip threshold. Check the cabinet’s airflow—the CHGB relies on forced air from the rack’s cooling fans. If the fans are clogged, you’ll see elevated temperatures across all channels. Clean the filters and check the fan speed.

Q: The amber LED on channel 7 is flashing, not steady. What does that mean?
Flashing amber indicates a pre-warning—the channel’s temperature is above 75°C but below the 85°C trip threshold. The board is telling you it’s getting hot but hasn’t shut down yet. The CPU can use this as a maintenance alert. You’ll still get the output, but you should investigate airflow or load current. This is a new feature on the CHGB—the CHGA would only show steady amber after the trip occurred.

Q: Can I mix CHGA and CHGB boards in the same Mark V rack?
Yes. The backplane and firmware are compatible. The CPU will see the CHGB’s additional diagnostic channels if firmware v5.5+ is present; if not, it’ll ignore them. You can replace a failed CHGA slot with a CHGB without any configuration changes—the board will work in compatibility mode. However, if you want to use the thermal data, you’ll need to update the I/O map (as described above).

Q: What’s the maximum operating temperature with all 8 channels at 4A?
The CHGB’s extended operating range is 65°C ambient. However, at 65°C ambient with all 8 channels at 4A, the case temperature will approach 85°C and the board may trip. GE recommends derating the output current by 2.5% per °C above 50°C. At 60°C ambient, you should limit each channel to 4.5A. At 65°C ambient, limit to 4.0A. If you need full 5A, keep the ambient below 50°C and ensure good airflow (at least 100 CFM through the rack).

Q: How do I read the per-channel temperature data?
Through the Mark V Toolbox—navigate to the I/O map, select the slot with the CHGB, and you’ll see diagnostic registers for each channel. The temperature is reported in °C as a 16-bit integer. You can map these to alarms in the CPU logic: e.g., if ChannelTemp > 75°C, set a warning flag; if > 85°C, set a fault. Some plants also log the temperatures to the plant historian for trending. The temperature data updates about once per second.

Q: The CHGB is showing a current reading on a channel that’s turned off. What’s the most likely cause?
Leakage current. When the MOSFET is off, there should be 0A. If you’re reading 50-100mA, that’s normal leakage through the output protection circuit. If it’s above 100mA, the output MOSFET may be partially shorted (we’ve seen this after a voltage transient). Check the actual output voltage with a multimeter—if you’re reading more than 5V when OFF, the MOSFET has failed. If it’s 0V but the current is showing 50mA, it’s just leakage; you can ignore it or adjust the threshold in the CPU logic to ignore readings below 200mA.

Q: Does the CHGB support external snubbers for inductive loads?
The board already has built-in flyback diodes. However, for large inductive loads (e.g., contactors with 5H coils), the flyback diode may not clamp the voltage quickly enough—we’ve seen spikes up to 300V on 125VDC lines. If you’re switching large inductive loads, install an external RC snubber (e.g., 100Ω + 0.1µF) across the load to dampen the spike. The CHGB’s MOSFETs are rated for 200V, so a 300V spike could damage them. This is especially important for 125VDC operation.

Q: What’s the lead time for a surplus CHGB?
We keep 3-5 units in stock. Domestic: 2-3 business days ground, overnight if ordered by 2 PM EST. International: 5-7 days via DHL. This board is subject to ITAR regulations—we’ll need an end-user certificate for international shipments. We include a GE certificate of origin and commercial invoice with every shipment. If you need expedited international shipping, we can arrange DHL Express Same-Day or hand-carry options (additional cost). Contact us for details.

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