Time Delay Relays

Part Number	Description / PDF	Quantity
TDI120AL Wickmann / Littelfuse	RELAY TIME DELAY	29
KRPSD22S Wickmann / Littelfuse	RELAY TIME DELAY PROGRAMMABLE	0
KRDB217S Wickmann / Littelfuse	RELAY TIME DELAY D.O.B.	0
T2D120A15M Wickmann / Littelfuse	RELAY TIME DELAY 5MIN CHASSIS	13314
ESDR420A4 Wickmann / Littelfuse	RELAY TIME DELAY SS RECYCLING	2
KSDB314SP Wickmann / Littelfuse	RELAY TIME DELAY SOLID STATE TMR	0
TDM24AL Wickmann / Littelfuse	RELAY TIME DELAY DIGI-SET D.O.M.	6
ESDR423A4 Wickmann / Littelfuse	RELAY TIME DELAY SS RECYCLING	0
KRDR321A4 Wickmann / Littelfuse	RELAY TIME DELAY RECYCLING TIMER	0
KRDS221 Wickmann / Littelfuse	RELAY TIME DELAY SINGLE SHOT	7
KRDR121A1 Wickmann / Littelfuse	RELAY TIME DELAY RECYCLING TIMER	0
KSDB134P Wickmann / Littelfuse	RELAY TIME DELAY SOLID STATE TMR	12
TDUB3002A Wickmann / Littelfuse	RELAY TIME DELAY DELAY ON BREAK	0
T10120 Wickmann / Littelfuse	RELAY TIME DELAY ON ADJ 115V	0
KRPSD22M Wickmann / Littelfuse	RELAY TIME DELAY PROGRAMMABLE	1
ESDR420B1 Wickmann / Littelfuse	RELAY TIME DELAY SS RECYCLING	0
FA155 Wickmann / Littelfuse	RELAY TIME DELAY SOL ST AUX MOD	2
THDB434C Wickmann / Littelfuse	RELAY TIME DELAY DIGI-PWR D.O.B.	42
KRDR440.5SA0 Wickmann / Littelfuse	RELAY TIME DELAY RECYCLING TIMER	0
TSD6310.8SN Wickmann / Littelfuse	RELAY TIME DELAY INTERVAL DIGI	3

Time Delay Relays

1. Overview

Time Delay Relays (TDRs) are control devices that execute switching operations after a predetermined time interval. They integrate timing functions into electrical systems to manage sequence operations, protect equipment, and optimize process efficiency. Modern industrial automation relies on TDRs for precise control in applications ranging from motor startups to complex manufacturing processes.

2. Main Types and Functional Classification

Type	Functional Characteristics	Application Examples
On-Delay Relay	Delays contact closure after power application	Motor soft start, conveyor belt synchronization
Off-Delay Relay	Delays contact opening after power removal	Fan cooling systems, oven shutdown sequences
Interval Timer	Controls fixed-duration outputs	Valve actuation, injection molding cycles
Repeat Cycle Timer	Alternates between on/off states	Conveyor indexing, periodic lubrication systems

3. Structure and Components

Typical TDR construction includes:

Enclosure: Flame-retardant polymer housing (IP20-IP67 ratings)
Electromagnetic System: Coil assembly with laminated iron core
Contact Mechanism: Silver alloy contacts (NO/NC configurations)
Timing Circuit: Analog RC circuits or digital microcontrollers
User Interface: Dial/potentiometer or digital display for setting adjustment

4. Key Technical Specifications

Parameter	Typical Range	Importance
Timing Range	0.1s-999h	Determines application flexibility
Accuracy	1% to 10ms	Critical for precision processes
Power Supply	12-240V AC/DC	Matches system voltage requirements
Contact Rating	5-30A resistive	Ensures load compatibility
Ambient Temp. Range	-20 C to +70 C	Operational reliability factor

5. Application Areas

Primary industries include:

Manufacturing: Press machine sequence control
Energy: Transformer cooling systems
Building Automation: HVAC fan delay control
Process Industry: Pump alternation systems
Transportation: Railway signal timing

Typical equipment integration: CNC machines, packaging lines, water treatment systems.

6. Leading Manufacturers and Products

Manufacturer	Key Product Series	Distinguishing Features
Siemens	3RP25/3RP15 series	DIN rail mounting, LED status display
Omron	H3CR-A/-M models	Multi-voltage capability, compact design
Schneider Electric	Tesys T-ModTime series	Modbus communication, 12 timing functions
AutomationDirect	DL-TDR series	Programmable via USB interface

7. Selection Recommendations

Key considerations:

Timing function type (ON/OFF delay, interval, etc.)
Environmental conditions (temperature, vibration)
Electrical requirements (voltage/frequency compatibility)
Mounting method (DIN rail, panel mount, socket mounting)
Agency approvals (CE, UL, CSA standards)

Case Study: A bottling plant successfully implemented Omron H3CR-M timers for conveyor synchronization, achieving 15% throughput improvement.

8. Industry Trends

Emerging developments include:

Integration with Industrial IoT (remote monitoring via Ethernet/IP)
Adoption of solid-state relay technology (SSR) for higher switching speeds
Energy-efficient designs meeting Ecodesign Directive 2019/1782
AI-enhanced predictive timing adjustment in smart manufacturing