ABB CT Time Relays

On-delay timers delay an output after the specified trigger; off-delay timers keep an output active for a set interval after the trigger changes. Pulse, cyclic and star-delta timing are other functions available within ABB’s CT portfolio. These functions can support delayed starting, timed switching, sequencing and motor-starter changeover. Not every CT relay provides every function, and a timer does not replace the contactor or protective device required by the application.

CT-C, CT-S & CT-D Product Ranges

• CT-C: compact time relays in a 17.5 mm housing. Existing references on this page include CT-MFC, CT-ERC, CT-AHC and CT-TGC.
• CT-S: the industrial time-relay range with screw and push-in connection options. Existing references include CT-MVS, CT-MFS, CT-MBS, CT-ERS, CT-APS and CT-SDS.
• CT-D: modular DIN-rail time relays for installation and distribution panels, in a 17.5 mm housing. Existing references include CT-MFD, CT-ERD, CT-AHD and CT-TGD.

The platform names and timing functions describe different aspects of a product. Use the complete designation and ABB product data to confirm the combination; the examples above do not imply that every range has the same functions, terminals or supply voltage.

Timing, Wiring & Output Selection

Choose the required delay or cycle and check that it lies within the selected device’s adjustable time range. Confirm how timing starts, resets and responds to loss of the control supply. Off-delay devices may require an auxiliary supply, and multifunction devices require the correct function setting and wiring diagram.

Check control-supply voltage, AC/DC suitability and frequency separately from the voltage and current switched by the output contacts. Confirm the required number of changeover or normally open contacts, the load type and the corresponding contact rating. A contact rating for a resistive load must not be assumed to cover a contactor coil or another inductive load.

For installation, confirm DIN-rail space, terminal technology, permitted conductor size, terminal identification and any control input or remote adjustment required by the exact model. Use its ABB instructions for connection details. For star-delta starting, confirm the selected timer’s changeover sequence and transition interval together with the starter’s contactor and interlock design.

Confirming a Specific CT Model

Provide the intended timing function, desired time range, control supply and the load to be switched. Check output-contact arrangement, trigger/reset method, terminal type, mounting space and ambient conditions. Confirm the applicable standards and regional approvals in the exact product documentation; a family description does not establish IEC, UL or railway approval for every listed reference.

For an existing installation, send the full model and ABB code, a readable nameplate photo and the existing wiring or application details. Older references remain in the table; specifications or replacement suitability must be checked individually.

Related pages: Relays & Monitoring and Contact.

ABB references: CT time-relay overview; CT-C; CT-S; CT-D.