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Timers
Application Notes
Sequencing Independent Adjustment Sequence (Single Cycle):
Upon momentary closure of start switch, CR1 is energized and
latched on through its normally open contact CR1a. This closed
contact in turn feeds power to both the TDM1 coil and (through
normally closed TDM1 contacts) load 1. When TDM1 time delay
is complete, TDM1 normally open contacts (1 and 3) close and its
normally closed contacts (1 and 4) open, removing power from
load 1. Load 2 is now energized through TDM1 contacts (1 and 3)
and through TDM2 normally closed contacts (1 and 4). TDM2 coil
is also powered and begins timing. This sequence continues for
TDM3 (and load 3) and TDM4 (and load 4) as shown in the Time
Diagram until TDM4 completes its time cycle; at which point its
normally closed contacts (1 and 4) open and unlatch CR1, resetting
the entire circuit. Press start button again to repeat another cycle.
(TDM can be replaced by TRM or PRM. Also applicable would be
ORM or ERDM; however, pin numbers are different.)
Staging (ON and OFF): On closure of SW1, Load 1 is energized
and a time sequencing ON condition is initiated. At the end of the
T1 ON delay, Load 2 is energized which in turn initiates the ON delay
of timer T2. When the second ON delay is completed, Load 3 is
energized. Additional TDMB Time Delay Relays can be connected
to operate additional loads. With the opening of SW1, each load in
the system is sequenced OFF starting with Load 1 and continuing
with Load 2, then Load 3.
T1, T2 = TDMB
CR1 = Electromechanical Relay
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Timers
Application Notes
Dual Momentary Timing (With Lockout): Both timing circuits are
of the single shot type. Because of the normally closed contacts
in series with each push-button, one circuit is disabled when the
other is in use.
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Plug-in Timers: The three-wire PS will operate with all plug-in timers
as shown in Figures 1A and 1B.
Two-wire proximity devices have minimum load requirements.
The load resistor Rd shown in Figure 2 & 3 is necessary for proper
operation of the proximity device. See proximity data sheets for
correct load values.
Figure 2
TDB, TRB, TDS, TRS
Figure 3
TDM, TRM, TDR, TDI
Pulse Shaping: (Fig. 3) For pulse shaping applications, the timer
coil is wired in series with the PS. Resistor Rd may be required for
proper operation of the PS.
T1 and T2 = TS2, TS4, TSD2, TSD4,
Also see ORS and ERDI
Solid State Timers: The three-wire PS can be wired directly to most
solid state timers as shown in Figures 4A through 4D.
Using Proximity and Photoelectric
Switches with Timers
The Characteristics of Proximity and Photoelectric Switches, also
known as solid state electric switches can successfully be used
with timers. Typically, a two-wire proximity or photoelectric switch
will leak approximately 2.5 milliamperes of current when in its
OFF state. The three-wire proximity and photoelectric switches
exhibit little, if any, leakage current. The following circuits show
the various interfacing of proximity or photoelectric switches
(PS) with timers.
Figure 1A
TRS, TDS, TRB, TDB
Figure 1B
TRM, TDM, TDI, TDR
Figure 4A
TS1, TSD1, TDU, KSDI,
TSU2000, TMV8000
Figure 4C
TSDS, TSDB
Figure 4B
TS2, TSD2, TSDR, TSD3,
KSD2, KSDR
Figure 4D
RS Series
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Timers
Application Notes
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Solid State Timers (continued from previous page): In some
applications, an interfacing device may be required as shown in
Figure 5. A simple relay interface would provide the dry closure
required by this series of timers. Note: This same principle can be
used with the two-wire PS.
Timers TS2 and the TSDR Series do not require a shunt resistor
and can be operated efficiently with two-wire PS as shown in Fig.
8. Be aware that the application of a two-wire PS with solid state
timers is varied. If you do not find your application in these notes,
contact our Technical Assistance Department about your specific
requirements.
Figure 8
TS2, TSDR
Figure 5
TSB, TSS
Leakage Current: (Control of) Solid state switches have an ON
resistance of about 5 to 10 ohms and an OFF resistance of a few
hundred thousand ohms causing a certain amount of leakage
through the solid state switch during the OFF state. This leakage
can present problems. The leakage current of the two-wire type
PS may result in premature timing of the two-terminal solid state
timers. This leakage current can be redirected by using a shunt
resistor Rs as shown in Figures 6 and 7.
Possible Shunt Resistor Values (Rs)
Voltage
24VAC
24VAC
24VAC
120VAC
120VAC
120VAC
240VAC
240VAC
240VAC
Value in Ohms
100 270
470
2,500
5,000
10,000
6,000
10,000
27,000
Power in Watts
NOTE: Due to a number of variables, we urge you to
consult our Technical Assistance group or that of the
switch manufacturer.
Rs = 10K, 2W at 120VAC
Figure 6
TSD2, TSD3
Rs = 2.5K, 10W at 120VAC
Figure 7
TS1, TSD1, TDU,
TMV8000, TSU2000
7
3
2
10
5
2
10
7
3
Timers
Application Notes
Random Start: Random start timing is a common practice used
to prevent overloading of power lines and the reducing of peak
demand levels. In industrial and commercial locations where
numbers of compressors are used for air conditioning, heating,
refrigeration, compressed air, and electric heating elements are
used to heat air, water, or in process equipment, it is important
that all of this equipment not start at the same time. This can
happen in the case of a power failure or with night shutoff
systems. If simultaneous starting is allowed, damage can occur
due to low voltage starts.
One way to correct this situation is to provide a Random Start
system. This is accomplished by placing a timer in each piece of
equipment to delay start. These timers are set at different times
so that a staggered or random start situation is achieved.
NOTE: Also see TMV8000 and TSU2000
Thermistor Controlled Timer: This application utilizes a negative
temperature coefficient (NTC) thermistor to change the time
delay as a function of temperature. NTC thermistors decrease
in resistance as temperature increases. In this case, the OFF
time is being varied. As the temperature increases, the cycles
per minute increase as a result of a shorter OFF time.
TSDR445SA0
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Part Winding Start: The following is a typical wiring diagram for
reduced torque starting of a 2 winding, 3 phase motor.
Upon closure of the Start button, 1MC is energized and TAC1 begins
its time delay. At the end of TAC1’s time delay, 2MC is energized. The
circuit is reset upon opening of Stop button or O.L. contact.
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Timers
Application Notes
Air Compressor Drain, Automatic Operation: Upon application of power, the external adjustable 1 to 100 minutes OFF time delay begins.
At the end of the OFF period, a fixed ON time of 2 seconds is initiated which energizes the solenoid, and drains the condensation
commonly built up in a compressor. OFF/ON recycling continues until the input power is removed. The KSPD and ESDR Series are
also available featuring onboard or remotely adjustable ON and OFF time delay control.
Timers
Application Notes
Flow Monitor (Delay on Make Normally Closed): Flow monitoring
is used in industrial applications where a continual flow of product
is necessary, and can terminate the operation if the flow is not
detected. Upon closure of SW1, T1 time delay is initiated and relay
CR is energized. When the normally open contacts of relay CR
close, energizing the pump, the resulting flow (Int. #1) opens flow
switch SW2. Each time SW2 opens, T1 time delay is set to zero.
(Int. #2) As long as SW2 remains open, timing will not progress.
Should the SW2 flow switch close and re-open before the end of
the T1 time delay, the pump will stay energized. When the flow
switch SW2 closes and remains closed for a period longer than
the T1 time delay (Int. #3), T1 de-energizes the control relay and
disconnects the pump. To reset, open SW1.
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Motion Detectors,
Zero Speed Switch a Low Cost Approach
Many conveyor systems use a logic control module as an interface
between the proximity or photoelectric switch and its associated
load. The KRD9, KRPS, KSPS, NHPS, HRD9, TRDU, and TRU
series of low cost Timers/Controls (retriggerable single shot
function) are designed to detect motion and/or zero speed by
monitoring the pulses from an external photoelectric or proximity
switch. These pulses continuously reset the control’s timing circuit,
preventing it from completing its selected time delay. If a pulse
is missing, the control completes its time delay and the output
changes state.
To operate correctly, 2-wire proximity and photoelectric switches
require a “leakage” or “residual” current flow during their OFF state.
See Application Notes: Leakage Current (Control of) for possible
(shunt) limit resistor values table.
In the diagram shown, the conveyor motor (CR1) starts when SW1
start switch closes. The conveyor establishes the pulse train which
is sensed by SW2, a two wire photo switch. Each time an object
is sensed by SW2, it resets the timing circuit of the timer and the
conveyor continues to run. If SW2 stops sensing moving objects,
(the pulses are interrupted), the timer completes its time delay and
de-energizes the conveyor contactor coil (CR1). The N.C. stop
switch immediately turns OFF the conveyor when it opens.
T1 = TSD4, THD4, KSD4
Pump Control: Upon closure of float switch, FS1, the delay on make
time delay is initiated. This time delay will be reset if the float switch
does not stay closed for the duration of the ON delay. At the end
of the ON time delay, the pump motor is energized and will remain
in this condition if no further action is taken. When the float switch
opens, the motor stays running for the length of the delay on break
time delay, then shuts off. Should the FS1 be reclosed during the
delay on break period, the OFF delay will reset to zero.
T1 = TDMB
Our line of Motion Detectors/Zero Speed Switches/Retriggerable
Single Shot Timers are designed for use in conveyor, elevator,
escalator, and process control applications. They are available in
encapsulated or un-encapsulated versions, and with solid state
or relay outputs.