GE HE693THM809C PLC Module

This PLC module provides thermocouple input capability for GE Series 90-30 automation systems. It connects directly to temperature sensors without external signal conditioning. Therefore, it enables precise temperature measurement for industrial heating and process control applications.

Physical and Analog Specifications

The GE HE693THM809C measures 12.5 cm in length and 9.0 cm in width. Moreover, its module weight equals approximately 0.30 kg for rack mounting. A single 20-pin removable terminal block handles all field wiring connections. Additionally, this module contains eight independent thermocouple input channels.

Parameter	Specification
Brand	General Electric (GE)
Full Model	HE693THM809C
Category	PLC Module (Thermocouple Input)
Dimensions (L x W x H)	12.5 cm x 9.0 cm x 5.5 cm (4.92″ x 3.54″ x 2.17″)
Module Weight	0.30 kg (0.66 lbs)
Primary Interface	1 x 20-pin Removable Screw Terminal Block
Backplane Interface	1 x 48-pin Male Connector (Series 90-30 Rack)
Operating Voltage	5 VDC from Backplane (0.4 A Typical)
Power Consumption	2.0 W (Typical)
Analog Input Channels	8 Differential Channels
Input Type	Thermocouple (Direct Connection)
Supported Thermocouples	Types J, K, T, E, R, S, B, N
Input Voltage Range	-10 mV to +70 mV (Thermocouple Range)
Cold Junction Compensation	Internal (Automatic per Channel)
Resolution	16 Bits (0 to 65535 Counts)
Conversion Type	Sigma-Delta
Conversion Speed	80 ms per Channel (640 ms for All 8 Channels)
Absolute Accuracy	±0.4% of Full Scale at 25°C
Accuracy Drift	±0.02% per °C
Common Mode Rejection	120 dB (50/60 Hz)
Normal Mode Rejection	80 dB (50/60 Hz)
Input Impedance	2 MΩ (Typical)
Maximum Input Voltage	±30 VDC (Continuous)
On-Board Components	1 ADC Chip + 8 Signal Conditioning Circuits + 2 Temperature Sensors (CJC) + 8 Protection Diodes + 1 EMI Filter + 1 Voltage Reference IC + 1 Microcontroller + 2 Memory Chips
Energy Storage	2 x 100 µF Electrolytic Capacitors (35V) + 2 x 10 µF Tantalum (25V)
Isolation Rating	1500 Vrms (Field to Backplane)
Operating Temperature	0°C to +55°C (32°F to 131°F)
Storage Temperature	-25°C to +85°C (-13°F to 185°F)
Mounting Type	Series 90-30 PLC Rack (Single Slot)
Status Indicators	1 Green LED (Power) + 1 Green LED (Active) + 1 Red LED (Fault) + 8 Green LEDs (Channel Valid)

Thermocouple Input and Cold Junction Compensation

The GE HE693THM809C accepts direct connection from eight common thermocouple types. Specifically, Types J, K, T, E, R, S, B, and N are all supported. In addition, an internal temperature sensor provides automatic cold junction compensation per channel. Moreover, the module linearizes each thermocouple signal for accurate temperature readings. Furthermore, the 16-bit resolution delivers 65,535 discrete counts for precise measurement. Consequently, you do not need external transmitters or signal conditioners for any channel.

High-Density and High-Resolution Features

This PLC module provides eight thermocouple channels in a single Series 90-30 slot. For instance, the 120 dB common mode rejection eliminates ground loop interference effectively. In addition, the 80 dB normal mode rejection filters 50/60 Hz power line noise. Moreover, the conversion speed of 80 milliseconds per channel suits multi-zone temperature control. Furthermore, the absolute accuracy of ±0.4 percent ensures reliable temperature control. Thus, this module handles large heating applications with many zones efficiently.

Energy Storage and Signal Integrity

This thermocouple input module stores energy using four onboard capacitors for power filtering. Specifically, two electrolytic capacitors smooth the 5 VDC supply for stable ADC operation. In addition, two tantalum capacitors provide high-frequency noise suppression for analog circuits. Furthermore, these capacitors maintain conversion accuracy during brief power interruptions. Moreover, the 1500 Vrms isolation protects the backplane from field wiring faults. Therefore, the GE HE693THM809C performs reliably in electrically noisy industrial environments.

Installation and Diagnostic Indicators

Eleven LED indicators provide operational status at a glance on this module. First, a green Power LED lights when the 5 VDC backplane supply is present. Second, a green Active LED flashes during normal analog conversion operation. Third, a red Fault LED indicates hardware errors or out-of-range temperatures. Additionally, eight green Channel Valid LEDs illuminate when each channel reads a valid thermocouple signal. Furthermore, the module includes a keying mechanism for correct rack insertion. Thus, you can diagnose sensor status instantly without external tools.