DS3800HFPC | Mark V Speedtronic Frequency/Counter Card

Description

Product Introduction

The DS3800HFPC is the 24V DC version of the frequency input board, designed for modern sensors that output 24V DC pulse signals rather than the 120V AC signals common in older installations. This board accepts 24V DC inputs from proximity sensors, encoders, and solid-state pulse generators, with a frequency range of 0-10kHz and 12-bit counting resolution. If your plant uses 24V DC field devices for speed measurement or flow totalization, the HFPC is the board you need.

We’ve used the HFPC in combined-cycle plants where turbine speed sensors are 24V DC proximity type. The board’s 0.5A per channel input current capacity is more than sufficient for most sensors—they typically draw 10-50mA. The frequency measurement accuracy is ±0.1% of reading, which is adequate for speed control and overspeed protection. The board’s status LEDs show input activity, and the input filtering (3ms or 10ms) can be jumpered to debounce noisy signals. The 24V DC input version is more common in modern installations than the 120V AC version, as new sensors tend to operate at lower voltages.

Key Technical Specifications

Compatible Replacement Models

Frequently Asked Questions (FAQ)

Q: What’s the difference between the HFPC and the HFPB?
A: The HFPC accepts 24V DC inputs, while the HFPB accepts 120V AC inputs. The HFPC is for modern sensors (proximity sensors, encoders), and the HFPB is for older magnetic pickups that output 120V AC. The input impedance and current draw are different—the HFPC has a 4.7kΩ impedance, while the HFPB has a 10kΩ impedance. Choose based on your sensor’s output voltage.

Q: Can I use the HFPC with a proximity sensor that outputs a 24V DC pulse?
A: Yes, the HFPC is designed for 24V DC pulse inputs. Proximity sensors typically output a voltage pulse when a target passes, which the HFPC counts. The board’s input voltage range (10-30V DC) covers standard 24V DC sensors.

Q: What’s the frequency range of the HFPC?
A: The HFPC measures frequencies from 0Hz to 10kHz, with ±0.1% accuracy. This covers the typical speed range of 60Hz turbines (up to 7.2kHz for a 120-tooth gear). The 12-bit resolution provides a count value for the Mark V to calculate speed. If you need higher frequencies (up to 100kHz), consider the HFPD variant.

Q: How does the HFPC measure frequency?
A: The HFPC counts pulses over a fixed time interval (typically 10ms) and provides a count value to the Mark V. The Mark V calculates frequency by dividing the count by the time interval. The board also has filter jumpers to debounce noisy signals (3ms or 10ms filter). For speed measurement, you typically use the 3ms filter for faster response.

Q: Can I use the HFPC for flow meter pulse counting?
A: Yes, the HFPC can count pulses from 24V DC flow meters. The count value can be used for totalization or rate measurement. However, the 10ms scan rate may not be sufficient for high-frequency flow meters (>10kHz). Check your flow meter’s output frequency before choosing the HFPC.

Q: The HFPC has a 0.8A backplane current draw. Is that lower than the HFPB?
A: Yes, the HFPC draws 0.8A, while the HFPB draws 1.0A. The lower current is due to the lower input voltage and reduced power consumption of the 24V DC inputs. The Mark V power supply is rated at 6A on the 5V rail, so the HFPC is within the limit. If your rack has multiple HFPC boards, check your total backplane current.

Q: Does the HFPC have conformal coating?
A: Not by default. The HFPC’s suffix typically indicates termination type, not coating. If you need conformal coating for harsh environments, look for a suffix with a “G” (e.g., DS3800HFPC1G1G). The standard HFPC is suitable for indoor environments. If your plant has high humidity or corrosive conditions, consider a coated variant.

GE DS200TCCBF2BDA
GE DS200TCCBF3BAG
GE DS200TCCBF3BAJ