Time Delay Relays – Application Data
Definition:
Time Delay is defined as the controlled period between the functioning of two events. A Time Delay relay is a combination
of an electromechanical output relay and a control circuit. The control circuit is comprised of solid state components and
timing circuits that control operation of the relay and timing range. Typical time delay functions include On-Delay, Repeat
cycle (starting off), Interval, Off-Delay, Retriggerable One Shot, Repeat cycle (starting on), Pulse Generator, One Shot,
On/Off Delay, and Memory Latch. Each function is explained in the table below. Time delay relays have a broad
choice of timing ranges from less than one second to many days. There are many choices of timing adjustments from
calibrated external knobs, DIP switches, thumbwheel switches, or recessed potentiometer. The output contacts on the
electromechanical output relay are direct wired to the output terminals. The contact load ratings are specified for each
specific type of time delay relay.
Understanding the differences between all the functions available in time delay relays can sometimes be a daunting task.
When designing circuits using time delay relays questions such as:
“What initiates a time delay relay?”
“Does the timing start with the application or release of voltage?”
“When does the output relay come on?”
must be asked.
Time delay relays are simply control relays with a time delay built in. Their purpose is to control an event based on time.
The difference between relays and time delay relays is when the output contacts open & close: on a control relay, it
happens when voltage is applied and removed from the coil; on time delay relays, the contacts will open or close before
or after a pre-selected, timed interval.
Typically, time delay relays are initiated or triggered by one of two methods:
• application of input voltage (On Delay, Interval On, Flasher, Repeat Cycle, Delayed Interval & Interval/Flasher).
• opening or closing of a trigger signal (Off Delay, Single Shot & Watchdog).
These trigger signals can be one of two designs:
• a control switch (dry contact), i.e., limit switch, push button, float switch, etc.
• voltage (commonly known as a power trigger).
To help understand, some definitions are important:
Input Voltage:
Control voltage applied to the input terminals (see wiring diagrams below). Depending on the function,
input voltage will either initiate the unit or make it ready to initiate when a trigger signal is applied.
Trigger Signal:
On certain timing functions, a trigger signal is used to initiate the unit after input voltage has been applied.
As noted above, this trigger signal can either be a control switch (dry contact switch) or a power trigger (voltage).
Output (Load):
Every time delay relay has an internal relay (usually mechanical) with contacts that open & close to control
the load. They are represented by the dotted lines in the wiring diagrams. Note that the user must provide the voltage to
power the load being switched by the output contacts of the time delay relay.
The following tables contain both written and visual descriptions on how the common timing functions operate. A Timing
Chart shows the relationship between Input Voltage, Trigger Signal (if present) and Output Contacts.
SECTION 5
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M a gn e c r a ft S o lu t io n G ui de 1 0 5 A
FUNCTION DEFINITION TABLE
Function
A.
ON DELAY
Power On
B.
REPEAT CYCLE
Starting Off
C.
INTERVAL
Power On
D.
OFF DELAY
S Break
Operation
When the input voltage
U
is applied, timing delay
t
begins. Relay contacts
R
change state after time delay is complete. Contacts
R
return to their shelf state
when input voltage
U
is removed. Trigger switch is not used in this function.
When input voltage
U
is applied, time delay
t
begins. When time delay
t
is
complete, relay contacts
R
change state for time delay
t.
This cycle will repeat
until input voltage
U
is removed. Trigger switch is not used in this function.
When input voltage
U
is applied, relay contacts
R
change state immediately
and timing cycle begins. When time delay is complete, contacts return to shelf
state. When input voltage
U
is removed, contacts will also return to their shelf
state. Trigger switch is not used in this function.
Input voltage
U
must be applied continuously. When trigger switch
S
is closed,
relay contacts
R
change state. When trigger switch
S
is opened, delay
t
begins.
When delay
t
is complete, contacts
R
return to their shelf state. If trigger switch
S
is closed before time delay
t
is complete, then time is reset. When trigger
switch
S
is opened, the delay begins again, and relay contacts
R
remain in
their energized state. If input voltage
U
is removed, relay contacts
R
return to
their shelf state.
Upon application of input voltage
U,
the relay is ready to accept trigger signal
S.
Upon application of the trigger signal
S,
the relay contacts
R
transfer and the
preset time
t
begins. At the end of the preset time
t,
the relay contacts
R
return to
their normal condition unless the trigger switch
S
is opened and closed prior to
time out
t
(before preset time elapses). Continuous cycling of the trigger switch
S
at a rate faster than the preset time will cause the relay contacts
R
to remain
closed. If input voltage
U
is removed, relay contacts
R
return to their shelf state.
When input voltage
U
is applied, relay contacts
R
change state immediately
and time delay
t
begins. When time delay
t
is complete, contacts return to
their shelf state for time delay
t.
This cycle will repeat until input voltage
U
is
removed. Trigger switch is not used in this function.
Upon application of input voltage
U,
a single output pulse of 0.5 seconds is
delivered to relay after time delay
t.
Power must be removed and reapplied to
repeat pulse. Trigger switch is not used in this function.
Upon application of input voltage
U,
the relay is ready to accept trigger signal
S.
Upon application of the trigger signal
S,
the relay contacts
R
transfer and
the preset time
t
begins. During time-out, the trigger signal
S
is ignored. The
relay resets by applying the trigger switch
S
when the relay is not energized.
Input voltage
U
must be applied continuously. When trigger switch
S
is closed,
time delay
t
begins. When time delay
t
is complete, relay contacts
R
change
state and remain transferred until trigger switch
S
is opened. If input voltage
U
is removed, relay contacts
R
return to their shelf state.
Timing Chart
U
R
U
R
U
t
on
off
on
off
t
t
t
t
t
t
t
t
t
R
U
S
R
close
open
on
off
t
t
E.
RETRIGGERABLE
ONE SHOT
U
R
on
off
t
t
F.
REPEAT CYCLE
Starting On
G.
PULSE
GENERATOR
H.
ONE SHOT
U
R
U
R
U
S
R
U
S
R
U
S
R
close
open
on
off
close
open
on
off
close
open
on
off
on
off
on
off
t
t
t
t
t
t
Pulse
t
Pulse
t
t
I.
ON/OFF DELAY
S Make/Break
t
t
t
t
J.
MEMORY LATCH
S Make
Input voltage
U
must be applied continuously. Output changes state with every
trigger switch
S
closure. If input voltage
U
is removed, relay contacts
R
return to
their shelf state.
S
= Trigger Switch
R
= Relay Contacts
t
= Time Delay
U
= Input Voltage
Magnecra f t So l u t io n Gu i de 1 0 5 A
5/3
SECTION 5
S
close
open
Advantages of the 820 Series Time Delay Relays
Output Indication
Red LED Light.
Time Setting
Select Between 10 Different Time Scales.
Input Indication
Green LED Light.
Fine Time Setting
Ultimate Control in Accuracy.
Input Terminals
Accepts up to a
14 AWG Wire.
Function
Choose Between 10
Different Functions.
SECTION 5
DIN Rail Mounting
Mounts Directly On a DIN Rail.
5/4
M a gn e c r a ft S o lu t io n G ui de 1 0 5 A
The new 820 Series Time Delay Relays are DIN rail mountable products offering 10 different
timing functions, 2 status LEDs, ultra-wide timing range (0.1 sec to 10 days) and a universal
voltage input (12-240 VAC/VDC) all in one modular package.
The 821 is available as a 15 amp SPDT timer while its counterpart 822 is available as a DPDT
timer also capable of switching up to 15 amps per pole.
• Offers a “one stop solution” for
your
power management system.
Solid State Circuitry
Used for Time and
function Control.
• Available in both SPDT and
DPDT
contact configuration.
• The two LED status indicators
indicate
status at a glance.
SECTION 5
• The Green LED is on when
power is
applied to the input terminals. The Red
LED blinks during time-out, and is ON
when the output is energized.
• Color and appearance designed
for high
visibility in all environments.
Output Terminals
Accepts up to a
14 AWG Wire.
• Only 17.5 mm wide making it
ideal for
tight spaces.
• Engineering availability allows
for
customized relay solutions.
Optional Panel Adapter
(16-788C1)
See Section 3 p.18
www.magnecraft.com
Magnecra f t So l u t io n Gu i de 1 0 5 A
847-441-2540
5/5
820 Series Time Delay Relays/SPDT,
DPDT 15 Amp Rating
Input Indication
Green LED
Output Indication
Red LED
Time Setting
Fine Time Setting
Supply
Terminals
WHITE
WHITE
Function
Output Terminals
DPDT (822 Version
Only)
Output Terminals
DIN Mount
UL Listed
File No. E234203
General Specifications (@ 25°C)
Output Characteristics
Number and type of Contacts
Contact Material
Current rating
Switching voltage
(UL 508)
Units
821TD10H-UNI
SPDT
Silver Alloy
15
240 AC, 50/60 Hz
24 DC
1/2 @ 120VAC
1 @ 240 VAC
B300
100
Red
12….240
85% to 110%
3
1.7
Green
A,B,C,D,E,F,G,H,I,J
10
0.1….1
1….10
0.1….1
1….10
0.1….1
1….10
0.1….1
1….10
5
0.2
150
50
100,000
10,000,000
2500 AC
1000 AC
14 (2.1)
7.1 (0.8)
UL, CE
-30…+70
-20…+55
IP 20
65
822TD10H-UNI
DPDT
Silver Alloy
15
240 AC, 50/60 Hz
24 DC
1/2 @ 120VAC
1 @ 240 VAC
B300
100
Red
12….240
85% to 110%
3
1.7
Green
A,B,C,D,E,F,G,H,I,J
10
0.1….1
1….10
0.1….1
1….10
0.1….1
1….10
0.1….1
1….10
5
0.2
150
50
100,000
10,000,000
2500 AC
1000 AC
14 (2.1)
7.1 (0.8)
UL, CE
-30…+70
-20…+55
IP 20
65
@ 240 VAC, 24 VDC
Minimum Switching Requirement
Indication
Input Characteristics
Voltage Range
Operating Range
Maximum consumption
LED
A
V
V
HP
HP
Pilot Duty
mA
Blinks = Timing
On = Energized
VAC / VDC
AC
DC
VA
W
% of Nominal
LED
(See page 5/3)
SECTION 5
Indication
Timing Characteristics
Functions Available
Time Scales
Time Ranges Available
sec
min
hr
Tolerance
Repeatability
Reset Time
Trigger Pulse Length
Performance Characteristics
Electrical Life
Mechanical Life
Dielectric strength
Terminal Wire Capacity
Terminal Torque (maximum)
Environment
Product certifications
Ambient air temperature
around the device
Degree of protection
Weight
Mechanical Setting
Constant Voltage and Temperature
Maximum
Minimum
Operations @ Rated Current (Resistive)
Unpowered
Input to Contacts
Between Open Contacts
day
%
%
ms
ms
V
V
AWG (mm2)
in lb (Nm)
Standard version
Storage
Operation
°C
°C
grams
5/6
M a gn e c r af t S ol u t i on G u id e 1 0 5 A
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a ft
uid
05
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