The GE IS200TBTCH1CBB Thermocouple Input Terminal Board is a specialized temperature measurement terminal board used within GE Industrial Control Systems. As a member of the TBTC board family, the IS200TBTCH1CBB Thermocouple Input Terminal Board accepts 24 thermocouple inputs and provides the field-side termination, cold junction compensation, noise suppression, and signal conditioning required for accurate temperature measurement in Mark VIe control architectures. The board supports Type E, J, K, S, and T thermocouples, and when used with the PTCCH2 I/O pack it additionally supports Type B, N, and R thermocouples, allowing the board to be matched to a wide range of industrial temperature sensors.
The IS200TBTCH1CBB Thermocouple Input Terminal Board is identified by the GE part numbering convention used throughout the Industrial Control Systems product line. The "IS200" prefix identifies the board as a GE Industrial Control Systems product, with "200" specifically indicating that the board is a base-level assembly. The "TBTC" acronym identifies the board's functional designation as a Thermocouple Input Terminal Board. The "H1" designation identifies the hardware group, while the "CBB" suffix identifies the artwork and functional revision combination, with the C revision providing the simplex configuration with two DC-type connectors. All digits are important when ordering or replacing any board, as boards of different revision levels may not contain identical hardware, and GE ensures backward compatibility of replacement boards while noting that different revision levels may not contain identical components.
The IS200TBTCH1CBB Thermocouple Input Terminal Board is available in two general configurations within the family: the TBTC_1C version for simplex applications, which has two DC-type connectors and provides capacity for 24 thermocouple inputs with two I/O packs, and the TBTC_1B version for simplex and TMR applications, which has six DC-type connectors and provides capacity for 24 thermocouple inputs in simplex with two I/O packs connected to JRA and JTB, or 12 thermocouple inputs in TMR configurations. The IS200TBTCH1CBB Thermocouple Input Terminal Board is the C revision of the H1 board, providing the simplex configuration that is widely used in Mark VIe control systems.
This product introduction provides detailed technical information, functional descriptions, connector assignments, configuration guidance, and comprehensive specifications for the GE IS200TBTCH1CBB Thermocouple Input Terminal Board, serving as an essential reference for control system engineers, maintenance technicians, and system integrators working with GE industrial control equipment.
Functional Architecture and Signal Processing
The IS200TBTCH1CBB Thermocouple Input Terminal Board is built around a robust thermocouple measurement architecture that supports 24 thermocouple inputs, each with noise suppression, cold junction compensation, and hardware limit checking. The board performs several distinct functions that ensure accurate and reliable temperature measurement in electrically noisy industrial environments.
The 24 thermocouple inputs of the IS200TBTCH1CBB Thermocouple Input Terminal Board are wired to two barrier-type terminal blocks mounted on the terminal board. Each block has 24 terminals accepting up to #12 AWG wires, and a shield terminal strip attached to chassis ground is located on the left side of each terminal block to ensure proper shielding and grounding of the thermocouple cables. The terminal blocks can be unplugged from the board for maintenance, simplifying field wiring and board replacement. The thermocouples can be either grounded or ungrounded, providing flexibility for different installation requirements.
The IS200TBTCH1CBB Thermocouple Input Terminal Board accepts Type E, J, K, S, and T thermocouple inputs, and when connected to the PTCCH2 I/O pack it additionally accepts Type B, N, and R thermocouples. The input span is −8 mV to +45 mV when the board is connected to the PTCCH1 or VTCCH1, and −20 mV to +95 mV when connected to the PTCCH2 or VTCCH2. The board also accepts millivolt inputs, allowing it to be used for low-level voltage measurement applications beyond thermocouple temperature measurement.
Cold junction compensation is provided by reference junction temperature measurement at two locations on each H1C terminal board, and the cold junction accuracy is 1.1 °C (2 °F). Because a 1 °F error in the cold junction compensation will cause a 1 °F error in the thermocouple reading, the cold junction accuracy is a critical factor in the overall measurement accuracy of the board. The cold junction signals go into signal space and are available for monitoring, and normally the average of the two is used. Acceptable limits are configured, and if a cold junction goes outside the limit, a logic signal is set.
Thermocouple Ranges and Limits
The IS200TBTCH1CBB Thermocouple Input Terminal Board supports full-scale input ranges for each thermocouple type, and the input voltages for different thermocouple types versus the minimum and maximum temperature ranges are defined in the technical documentation. Cold junction temperature ranges are assumed to be from −30 to 65 °C (−22 to 149 °F).
For the TBTC_1B and TBTC_1C boards, Type E thermocouples span from −51 °C at −7.174 mV to 593 °C at 44.547 mV, Type J thermocouples span from −51 °C at −6.132 mV to 760 °C at 42.922 mV, Type K thermocouples span from −51 °C at −4.779 mV to 1093 °C at 44.856 mV, Type S thermocouples span from −17.78 °C at −0.524 mV to 1760 °C at 18.612 mV, and Type T thermocouples span from −51 °C at −4.764 mV to 399 °C at 20.801 mV. These ranges cover the typical industrial temperature measurement requirements for each thermocouple type.
For the TBTC with PTCCH2, the additional Type B, N, and R thermocouples are supported, extending the measurement capability to higher temperatures and specialized applications. Type B thermocouples span from 0 °C at −0.0114 mV to 1800 °C at 13.593 mV, Type N thermocouples span from −51 °C at −3.195 mV to 1250 °C at 45.694 mV, and Type R thermocouples span from −17.78 °C at −0.512 mV to 1700 °C at 20.220 mV.
Cold Junction Compensation
The cold junction compensation function of the IS200TBTCH1CBB Thermocouple Input Terminal Board is critical for accurate thermocouple measurement, because thermocouples measure the temperature difference between the hot junction and the cold junction, and the cold junction temperature must be known to calculate the hot junction temperature. The board measures the reference junction temperature at two locations on each H1C terminal board, and the TMR H1B board has six cold junction references, of which only three are available with the I/O packs.
Hard-coded limits are set at −40 to 85 °C (−40 to 185 °F), and if a cold junction goes outside this range it is regarded as bad. Most cold junction failures are open or short circuit, and if the cold junction is declared bad, the backup value is used. This backup value can be derived from cold junction readings on other terminal boards or can be the configured default value, ensuring that the temperature measurement continues even if one cold junction sensor fails.
Simplex and TMR Configurations
The IS200TBTCH1CBB Thermocouple Input Terminal Board supports simplex configurations, using two I/O packs plugged into the board to obtain 24 thermocouple inputs. In the Mark VIe system, the board works with the PTCC I/O pack and supports simplex, dual, and TMR applications, with the board providing the field-side termination for the thermocouple signals and the I/O pack providing the analog-to-digital conversion and processing.
The board family also includes the TBTC_1B version for TMR applications, in which the thermocouple signals fan out to three J-connectors and the Mark VIe control systems accommodate 12 inputs. The IS200TBTCH1CBB Thermocouple Input Terminal Board is the simplex version with two DC-type connectors, providing 24 thermocouple inputs with two I/O packs, which is the appropriate configuration for simplex applications where redundancy is not required.
Diagnostics and Fault Detection
The IS200TBTCH1CBB Thermocouple Input Terminal Board provides comprehensive diagnostic capabilities that assist with system verification and fault isolation. Each thermocouple type has hardware limit checking based on preset, non-configurable high and low levels set near the ends of the operating range. If this limit is exceeded, a logic signal is set and the input is no longer scanned. If any one of the input hardware limits is set, it creates a composite diagnostic alarm.
Each terminal board connector has its own ID device that is interrogated by the I/O board. The board ID is coded into a read-only chip containing the terminal board serial number, board type, revision number, and the J connector location. If a mismatch is encountered, a hardware incompatibility fault is created, preventing the system from operating with incorrect or mismatched hardware.
When operating with the I/O processor, a very small current is injected into each thermocouple path. This is done to detect open circuits and is of a polarity to create a low temperature reading should a thermocouple open. This open-circuit detection feature ensures that a failed thermocouple is detected and reported, rather than causing an incorrect temperature reading that could lead to an inappropriate control action.
The diagnostics also monitor readings from all thermocouples, cold junctions, calibration voltages, and calibration zero readings, providing comprehensive coverage of the measurement chain and ensuring that any fault in the thermocouple, the wiring, or the board is detected and reported.
Configuration
The IS200TBTCH1CBB Thermocouple Input Terminal Board has no jumpers or hardware settings on the board. All configuration is performed through the system software and the I/O pack, simplifying installation and reducing the potential for configuration errors. The board's thermocouple type support and input span are determined by the I/O pack to which it is connected, with the PTCCH1 supporting E, J, K, S, and T thermocouples and the PTCCH2 supporting E, J, K, S, T, B, N, and R thermocouples, so the correct I/O pack must be selected for the application.
