What is a time delay relay?

A time delay relay (TDR) is an electronic control device that delays the switching of its output contacts for a predetermined time after input power is applied or removed. Common functions include delay-on-make (output delays after power applied), delay-on-break (output delays after power removed), interval timing, and recycling (repeated on/off cycles).

What is the difference between delay-on-make and delay-on-break?

Delay-On-Make (DOM): The output relay energizes after a set delay time once input power is applied. Used for motor start delays, sequencing. Delay-On-Break (DOB): The output relay stays energized and only de-energizes after a set delay once input power is removed. Used for fan run-on, coast-down timing.

Which SSAC time delay relay is most versatile?

The SSAC TRDU series offers the most versatility with 21 selectable timing functions in a single unit. It can replace almost any single-function timer. The TRU series is also highly versatile with 10 functions and easier knob adjustment. Both feature universal voltage input (19-264VAC) and 10A relay output.

What is the warranty on SSAC time delay relays?

All SSAC time delay relays come with an industry-leading 10-year warranty - far exceeding the 1-2 year warranty offered by most competitors. This reflects Littelfuse's confidence in SSAC product quality and reliability.

SSAC Time Delay Relays (TDR)

Name: SSAC Time Delay Relays
Brand: SSAC
Availability: InStock
Rating: 4.9 (156 reviews)

Gross Automation stocks the complete line of SSAC time delay relays - from versatile multifunction timers to specialized single-function units. All SSAC TDRs feature an industry-leading 10-year warranty and are available for same-day shipping.

Need a time delay relay? Talk to an expert:

262-252-1600

Same-Day Shipping on In-Stock Items

Search Time Delay Relays in Our Inventory

TRU Series HRDM TDUB Delay-On-Make

Time Delay Relay Categories

Multifunction Time Delay Relays

The most versatile SSAC timers - select your timing function via DIP switches or knobs. One timer, multiple applications.

Series	Functions	Voltage	Output
TRDU	21 selectable functions	19-264VAC/19-30VDC	10A DPDT
TRU	10 selectable functions	19-264VAC/19-30VDC	10A SPDT/DPDT
ASQU/ASTU	8 functions, knob adjust	24-240VAC/DC	5A SPDT
DSQU/DSTU	8 functions, DIP switch	24-240VAC/DC	5A SPDT

Download Multifunction Timer Catalog (PDF)

Delay-On-Make (DOM) Timers

Function: Output energizes after a set delay time once input power is applied. The delay resets when power is removed.

Applications: Motor start sequencing, compressor anti-short cycle, pump startup delays, soft-start timing.

Series: HRDM, KRDM, TDM/TDMH/TDML, ERDM, TRM, PRLM, ORM

Download DOM Timer Catalog (PDF)

Delay-On-Break (DOB) Timers

Function: Output stays energized and de-energizes after a set delay once input power is removed.

Applications: Fan run-on after motor stops, coast-down timing, light-off delays, process cool-down.

Series: HRDB, KRDB, TDB/TDBH/TDBL, TRB, ORB

Download DOB Timer Catalog (PDF)

Interval Timers (Single Shot)

Function: Output energizes immediately on trigger and de-energizes after set time. One pulse per trigger.

Applications: Dispensing controls, wash cycles, alarm timing, one-shot actuation.

Series: HRDI, KRDI, TDI/TDIH/TDIL, HRDS, KRDS, TDS, ERDI, ORS

Download Interval Timer Catalog (PDF)

Recycling Timers

Function: Output repeatedly cycles on and off at set intervals. Continuous repeat until power removed.

Applications: Duty cycling heaters, flashing lights, periodic pump operation, agitator timing.

Series: HRDR, KRDR, TDR, ERD3, KRD3

Download Recycling Timer Catalog (PDF)

Why Choose SSAC Time Delay Relays?

10-Year Warranty

Industry-leading warranty vs. 1-2 years from competitors

±0.1% Accuracy

TRU series offers exceptional repeat accuracy

Universal Voltage

Wide input ranges (19-264VAC) simplify inventory

Made for Industry

Robust construction for harsh industrial environments

Related SSAC Products

Solid State TDRs
100x longer life, no moving parts HVAC Timers
Compressor protection, fan delays Monitoring Relays
Voltage, phase, current monitors Full Catalog
All SSAC products with PDFs

Ready to Order SSAC Time Delay Relays?

Same-day shipping. Expert support. 10-year warranty.

Call 262-252-1600

Gross Automation - Your trusted SSAC Distributor Since 1992