Raychem HTC-915
Universal heat tracing control system
CAUTION: installation, configuration and commissioning should only be performed by properly trained personnel. Local regulations regarding the installation & safety must be followed.
Application
| Type | Surface sensing/ambient sensing |
| Area of use | Non-hazardous area indoors, typically panel mounted |
| Approval certification | CE marked ??, UL ??, EAC ?? TC RU C-BE.08.B.01634 (Kazakhstan, Belarus) For other countries contact your local Chemelex representative. |
Product Specification
| Temperature range controller | -60°C to 570°C in steps of 1 K |
| Control algorithms | EMR: Line sensing on/off, proportional ambient SSR: Line sensing on/off, proportional, proportional ambient, power limiting, soft start |
| Switching accuracy | 1 K |
Enclosure
| Ambient operating temperature range | -40°C to +50°C |
| Ambient storage temperature range | -40°C to +85°C |
| Relative humidity | 0% to 90% Non condensing |
| Ingress protection | Housing: IP40, Terminals: IP20 |
| Material | ASA-PC, color: green |
| Flammability class | V0 (UL94) |
| Mounting method | Panel mounting on 35 mm DIN rail |
WARNING: [AC symbol] Alternating current (IEC 60417-5032)
[DC symbol] Direct current (IEC 60417-5031)
Electrical Properties
| Connection terminals and cabling | Screw type terminals. All terminals suitable for stranded and solid core connection cables having a cross section between 0.5 and 2.5 mm² (24 to 12 AWG). The 915-HTC and 915-Alarm Relay connector outputs (240V) require ferrules on the connecting wires if stranded wires are used. The wires shall handle a minimum wire temperature of 75°C. |
| Supply voltage | CE/EAC: 100 Vac to 250 Vac, +10%/-10%, 50/60 Hz, 0.15 A to 0.06 A CSA: 100 Vac to 277 Vac, 50/60 Hz, 0.15 A |
| Power consumption | Max 20 VA with limiter connected |
| Control output | Contactor control output: (EMR) Electromechanical relay rated 3 A/250 Vac, 50/60 Hz Solid-state relay control output: (SSR) 12 VDC, 75 mA max. to drive normally open Solid state relays. Depending on the application, one, two or three phase switching elements have to be used. (Solid state relays are not included) |
| Switching capacity | Depends on the type of switch element used (The switch element is external) |
| Alarm output relay | CE/EAC: Relay contact rated 3 A/250 Vac, 50/60 Hz CSA: Relay contact rated 3A/277Vac, 50/60 Hz Output is user programmable to open or to close on alarm. |
Temperature Sensor
| Type | 100 Ω platinum Pt 100, 3-wire, α = 0.00385 Ω/°C. Can be extended with a three core shielded cable of maximum 20 Ω lead resistance per conductor. |
| Quantity | 2 RTD inputs available |
Communications
| Protocol | Modbus RTU or ASCII |
| Topology | Multidrop/daisychain |
| Cable | Single shielded twisted pair, 0.5 mm² (24 AWG) or larger |
| Length | Typical 2.7 km max @ 9600 Baud |
| Quantity | Up to 32 devices |
| Address | Programmable |
For technical support call Chemelex or write an E-mail to info@chemelex.com
Functional Overview
The Raychem HTC-915 is a full featured temperature control system for heattracing applications.
Connection Diagram and Terminal Assignments
The diagram illustrates the system architecture showing the HTC-915 Controller connected to various inputs (Power supply, PT100 inputs, Current Transformers for load and earth leakage) and outputs (Control Relay, Solid State Output, Alarm Output). It also shows the connection to an optional HTC-915 Limiter and external communication via RS485. The controller interfaces with configuration and set-up software via RS485.
Controller Terminal Assignments
| Term | Function |
|---|---|
| 1 | RTD 1 source |
| 2 | RTD 1 sense |
| 3 | RTD 1 common |
| 4 | Shield |
| 5 | RTD 2 source |
| 6 | RTD 2 sense |
| 7 | RTD 2 common |
| 8 | External Input + (Inhibit/override) |
| 9 | External Input - (Inhibit/override) |
| 10 | Communications (RS-485+) |
| 11 | Communications (RS-485 -) |
| 12 | Shield |
| 13 | Digital common (to Limiter 1) |
| 14 | +12Vdc out (to Limiter 2) |
| 15 | TX data (to Limiter 3) |
| 16 | RX data (from Limiter 4) |
| 17 | Mains Input (L1) |
| 18 | Mains Input (L2/ neutral) |
| 19 | Control relay output |
| 20 | Control relay output |
| 21 | Alarm relay output |
| 22 | Alarm relay output |
| 23 | PE |
| 24 | SSR control output + |
| 25 | SSR control output - |
| 26 | Load Current CT input |
| 27 | Load Current CT input |
| 28 | Shield |
| 29 | GF CT input |
| 30 | GF CT input |
Limiter Terminal Assignments
| Term | Function |
|---|---|
| 1 | Digital common (from HTC 13) |
| 2 | +12Vdc in (from HTC 14) |
| 3 | RX data (from HTC 15) |
| 4 | TX data (to HTC 16) |
| 5 | RTD 1 source |
| 6 | RTD 1 sense |
| 7 | RTD 1 common |
| 8 | Shield |
| 9 | Control relay output |
| 10 | Control relay output |
| 11 | Alarm relay output |
| 12 | Alarm relay output |
| 13 | Load Current CT input |
| 14 | Load Current CT input |
Operator Console & Operation
The console features an alpha-numeric LED display for messages and prompts, which scroll if longer than 6 characters. The local keypad has 6 keys for mode selection, with alternate functions accessible via the SHIFT key.
Quick Notes on Operation
Basic rules for efficient Console use:
- Use the SHIFT key followed by ALARM, MONITOR, or CONFIG to select the operating mode.
- Use ◀ and ▶ to move around in the menu.
- Use ENTER to enter a new menu, enter a new value, or select a menu item.
- Use BACK to exit the current menu or cancel an edit.
Key Functions:
| Key | Function |
|---|---|
| SHIFT | Activates alternate (shifted) function for the next key press. The SHIFT LED illuminates. Pressing SHIFT again cancels the alternate function. |
| TEST | When prefixed by SHIFT, switches console to Alarm mode. |
| BACK [SHIFT MONITOR] | Exits current menu or cancels edit. Moves cursor left when editing alpha-numeric parameters. When prefixed by SHIFT, switches console to Monitor mode. |
| ENTER [SHIFT CONFIG] | Selects item or accepts setting. Moves cursor right when editing alpha-numeric parameters. When prefixed by SHIFT, switches console to Configure mode. |
| ▲ / ▼ | Moves to previous/next item in a menu; increments/decrements value when editing. |
LED Indicators
The console includes eight LED indicators: Four indicate the operating mode (SHIFT, ALARM, MONITOR, CONFIG). Two status LEDs indicate alarm and control output status (alarm LED flashes on alarm condition). Two additional LEDs indicate external communications activity.
Configuration and Limiter Integration
Changing the Configuration
To change configuration: Position parameter, press ENTER to initiate edit. If locked, enter passcode. Use ◀/▶ keys to change value. Operation of ◀/▶ varies by data type. Must end edit session before switching modes.
Changing a Numeric Parameter
To change a numeric parameter (e.g., setpoint): Position parameter, press ENTER to initiate edit. If locked, enter passcode. The last digit blinks; use ◀/▶ to set value, use ▲/▼ to move between digits. To enter negative values, scroll to the first digit for "-". Press ENTER to save, or BACK to exit without saving.
Passcode Protection
The HTC-915 Controller offers passcode protection for its configuration. Any portion can be viewed when locked, but editing requires the passcode. New units are not password protected.
Using the HTC-915-CONT with an Optional HTC-915-LIM Limiter
The Limiter Connection Diagram shows the optional Limiter connected to the Controller. The 12 VDC power supply for the Limiter can be obtained from the HTC-915-CONT. Wiring for communications and optional current sensors is also indicated.
Programming the Limiter
To prevent unwanted changes, limiter settings have special restrictions. Changing the Limiter set point requires pressing SHIFT then CONFIG after setting the value via the controller interface. Uninstalling the limiter from the system is done via the Misc. Setup Sub-menu, requiring SHIFT then CONFIG to confirm removal.
Limiter Details
Limiter Current Sensor Input
The limiter can be configured to allow temperature overshoot if no current flows to the heating system (e.g., due to external heat sources like steam cleaning). Sensors are monitored for short circuit and cable breakage; an open/short input causes instantaneous tripping.
Limiter Outputs
Limiter Control Output: Typically operates an external electromechanical relay (EMR) to isolate the load from the mains supply in case of excessive over-temperature.
Limiter Alarm Output: Changes state (NC to NO) if the limiter is powered up for the first time after an outage, if the set point is exceeded and the limiter trips, if an RTD failure is detected, or if a limiter current transformer failure is detected.
Limiter Reset
The limiter must be reset manually after tripping. Resetting is only possible if the actual temperature is below the limit temperature minus the unit hysteresis. Reset methods include: pressing ALARM and SHIFT + RESET on the controller, holding the RESET key on the limiter for > 2 seconds, remotely via external input or DCS system (5-24 Vdc), or via serial interface.
Appendix - Configuration Sheets
Firmware versions V1.0X.
Basic Mode Menu
| Parameter | Configuration Mode Menu (Factory) | Configuration Mode Menu (User) |
|---|---|---|
| Control Setpoint | 68°F (20°C) | |
| Lo TS 1 | 14°F (-10°C) | |
| Lo Load | 1.0 A | |
| Switch Control Mode | Deadband | |
| Circuit Breaker | *n/a (30. A) | |
| Temp. Units | °C | |
| Feature Mode | Basic |
Advanced Mode Menus
| Parameter | Configuration Mode Menu (Factory) | Configuration Mode Menu (User) |
|---|---|---|
| Control Setpoint | 68°F (20°C) | |
| Lo TS 1 | 14°F (-10°C) | |
| Lo Load | 1.0 A | |
| Switch Control Mode | Deadband | |
| Circuit Breaker | *n/a (30. A) | |
| Temp. Units | °C | |
| Feature Mode | Basic |
TS Alarms Configuration Sub Menu
| Parameter | Factory | User |
|---|---|---|
| TS 1 Fail | Enable | |
| Lo TS 1 | Enable | |
| Lo TS 1 | 14°F (-10°C) | |
| Hi TS 1 | Disable | |
| Hi TS 1 | 212°F (100.0°C) | |
| TS 2 Fail | *n/a | |
| Lo TS 2 | Disable | |
| Lo TS 2 | Disable | |
| Hi TS 2 | *n/a | |
| Hi TS 2 | 14°F (-10°C) | |
| Lo TS 2 | Disable | |
| Lo TS Filter | *n/a | |
| Hi TS Filter | 212°F (100.0°C) | |
| Latch TS Alarms | 0 min | |
| CTL TS Fail | *n/a (0 min) | |
| Yes | ||
| Enable |
Other Alarms Configuration Sub Menu
| Parameter | Factory | User |
|---|---|---|
| Lo Load | Enable | |
| Lo Load | 1.0 A | |
| Lo Load Filter | 0 sec | |
| Hi Load | Disable | |
| Hi Load | *n/a (30.0 A) | |
| Hi Load Filter | *n/a (0 sec) | |
| Hi GFI | Enable | |
| Hi GFI | 20 mA | |
| Hi GFI Filter | 0 sec | |
| GFI Trip | Enable | |
| GFI Trip | 30 mA | |
| Lo Volt | Enable | |
| Lo Volt | 90 V | |
| Lo Volt Filter | 0 sec | |
| Hi Volt | Disable | |
| Hi Volt | *n/a (270 V) | |
| Hi Volt Filter | *n/a (0 sec) | |
| Lo Resist | Disable | |
| Lo Resist | *n/a (50%) | |
| Lo Resist Filter | *n/a (0 sec) | |
| Hi Resist | Disable | |
| Hi Resist | *n/a (50%) | |
| Hi Resist Filter | *n/a (0 sec) | |
| Nominal Resist | *n/a (6.00 Ω) | |
| Overcurrent Trip | *n/a (Enable) | |
| Switch fail | Enable | |
| HTC Reset | Disable | |
| C.B. Limiting | *n/a (Disable) | |
| Output Limiting | *n/a (Disable) | |
| Switch Limiting | *n/a (Disable) | |
| Contactor Count | Enable | |
| Contactor Count | 200,000 | |
| EEROM data Fail | Enable |
Point Setup Sub-Menu
| Parameter | Factory | User |
|---|---|---|
| Tag | TAG-(factory ID) | |
| Switch Control Mode | Deadband | |
| Prop Band | 5°F (3°C) | |
| Cycle time | *n/a (4°F (2°C)) | |
| Switch Rating | *n/a (10 min) | |
| Circuit Breaker | *n/a (30.0 A) | |
| Outlet Limit Mode | Disable | |
| Max. Power | *n/a (7200 W) | |
| Max. Current | *n/a (30.0 A) | |
| 3 Ph Pwr Calc | No | |
| TS Fail Mode | Off | |
| TS CTL Mode | TS1-Fail Off | |
| TS 1 Hi Limit | *n/a Disable | |
| TS 2 Hi Limit | *n/a Disable | |
| Volt Turns Ratio | 1.00 to 1 | |
| Current Turns Ratio | 1.00 to 1 | |
| Auto-cycle | Enable | |
| Auto-cycle Interval | 8 | |
| Auto-cycle Units | Hours | |
| Override Source | Remote | |
| Load Shedding | *n/a | |
| Limiter Cutout Temp. | *n/a (50.0°C) | |
| Limiter Current Sense | *n/a (Disable) |
Misc. Setup Sub-Menu
| Parameter | Factory | User |
|---|---|---|
| Temp. Units | °C | n/a |
| Version | V1.0X.XX | |
| Limiter version | *n/a (V1.0X.XX) | |
| Ext. Input | Not used | |
| Flash Alarm Output | Yes | |
| Alarm output | N.C. | |
| Language | English | |
| Passcode | 0 | |
| Scroll Delay | 0.15 secs | |
| Load Defaults | (See user manual) | |
| Limiter Installed | No |
Communication Setup Sub-Menu
| Parameter | Factory | User |
|---|---|---|
| Protocol | Modbus RTU | |
| Modbus Addr | *n/a (1) | |
| Modbus Sub Addr | *n/a (0) | |
| Baud Rate | Auto | |
| Parity | *n/a (None) | |
| Tx Delay | 0.06 secs |
* n/a: Parameter may only appear if certain features are enabled. Values shown in brackets are the Factory defaults if the settings are enabled.
This information defines the default 915 Series Control Module configuration as set by the Factory for firmware V1.0X. These settings are subject to change without notice. It is the user's responsibility to verify that all configuration parameters are chosen appropriately for the intended application.
Product Dimensions
Controller Dimensions: Approximately 90mm (height) x 75mm (width) x 105mm (depth).
Limiter Dimensions: Approximately 75mm (height) x 45mm (width) x 105mm (depth).
Installation
Ensure all personnel involved in installation, servicing, and programming are qualified and familiar with electrical equipment, their ratings and proper practices and codes.
Installation Location
Considerations should include expected atmospheric conditions, accessibility for maintenance, testing and ambient temperature. The conditions at the place of installation may affect load current ratings.
Operator Safety Considerations
Caution: Some wiring configurations will use more than one power source and all must be de-energized prior to performing any maintenance on a control circuit.
Warning: The HTC-915 control module must be protected by external over current and disconnect devices.
Mounting Procedures
The HTC-915-CONT and HTC-915-LIM are designed for installation on a standard 35 mm x 7.5 mm (EN50022 compatible) DIN rail. Pollution Degree 2, Altitude 0-2000m.
Maintenance
Operator Maintenance
The HTC-915 control system is designed to be a maintenance-free product.
Replaceable Parts
There are no user-serviceable parts in the HTC-915 series controller or accessories. The unit is designed to be easily changed out in the field in a matter of minutes. Any HTC-915 system component appearing inoperative should be returned to the nearest Chemelex office.
Cleaning
If the HTC-915 components require cleaning, a damp cloth may be used to wipe the units. This should only be done while the units are disconnected from their power source. Do not use any harsh chemicals or solvents, as this may damage the housing or finish.
Electrical Connection
Connections are made via screw connections suitable to accept cable diameters between 0.5 and 2.5 mm² (24 to 12 Awg). Either solid or stranded wires may be used.
Do not rely on the controller as a disconnect device!
Installation Notes
- If contact with live parts is possible while working on the unit, it must be completely isolated from the mains supply.
- Be aware that the unit might have cables connected to it which are powered from different sources.
- Magnetic or electric fields, e.g., from transformers, mobile phones or electrostatic discharge must be avoided in the vicinity of the instrument.
- Route input, output and supply lines separately.
- Arrange sensor cable extensions as twisted and screened cables. Do not run them close to power cables. The shield, if any, shall be earthed on the controller's side only.
- Fluctuations in the supply signals are only permissible within the specified tolerances.
Contact Information
North America
Tel: +1 800 545 6258
Email: info@chemelex.com
Latin America
Tel: +1 713 868 4800
Email: info@chemelex.com
Europe, Middle East, Africa, India
Tel: +32 16 213 511
Fax: +32 16 213 604
Email: info@chemelex.com
Asia Pacific
Tel: +86 21 2412 1688
Email: infoAPAC@chemelex.com
chemelex
©2025 Chemelex. All Chemelex marks and logos are owned or licensed by Chemelex Europe GmbH or its affiliates. All other trademarks are the property of their respective owners. Chemelex reserves the right to change specifications without notice.
Document Reference: Raychem-IM-INSTALL092-HTC915-EN-2504
