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W172DIP-5 参数 Datasheet PDF下载

W172DIP-5图片预览
型号: W172DIP-5
PDF下载: 下载PDF文件 查看货源
内容描述: RELAY REED DIL 5VDC\n [RELAY REED DIL 5VDC ]
分类和应用:
文件页数/大小: 210 页 / 7033 K
品牌: ETC [ ETC ]
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C L A S S  
APPLICATION DATA  
SSR  
INTRODUCTION:  
LOAD CONSIDERATIONS (cont.)  
SOLID STATE RELAY (SSR) is a relay with isolated input and output,  
whose functions are achieved by means of electronic components without  
the use of moving parts as found in Electromechanical relays.  
DC LOADS: All loads should be considered inductive and a Diode  
should be placed across the load to absorb any inductive surge on  
turnoff.  
PRINCIPLE OF OPERATION:  
RESISTIVE LOADS: Loads of constant value resistance are  
probably the simplest application of SSR's. Proper attention to the  
steady state current ratings and applied blocking voltage specifica-  
tions normally will result in trouble-free operation.  
Solid State Relays are similar to Electromechanical relays, in that both use  
a control circuit and a separate circuit for switching the load. When voltage  
is applied to the input of the SSR, the relay is energized by a light emitting  
diode. The light from the diode is beamed into a light sensitive semiconduc-  
tor which, in the case of zero voltage crossover relays, conditions the  
control circuit to turn on the output solid state switch at the next zero voltage  
crossover. In the case of nonzero voltage crossover relays, the output solid  
state switch is turned on at the precise voltage occurring at the time.  
Removal of the input power disables the control circuit and the solid state  
switch is turned off when the load current passes through the zero point of  
its cycle.  
LAMP LOADS: Incandescent lamp loads, though basically  
resistive, present some special problems. Because the resistance  
of a cold tungsten filament is about five to ten percent of the  
heated value, a large inrush current can occur. The period of the  
inrush current can range from one half cycle to several cycles.,  
depending on the thermal time constant of the filament. It is  
essential to verify that this inrush current is within the surge  
specifications of the SSR. Also check that the lamp rating of the  
SSR is not exceeded. This is a UL rating based on the inrush of a  
typical lamp. Because of the unusually low filament resistance at  
the time of turn-on, a zero voltage turn-on characteristic is  
particularly desirable with tungsten lamps.. It has been demon-  
strated that a zero voltage turn-on can extend the life of tungsten  
lamps by limiting inrush current.  
APPLICATIONS:  
Solid State Relays are specially suitable in many applications.  
Listed below are some typical applications.  
Microprocessor-based Controls.  
Computers and Computer Peripherals.  
Process control Systems using PLCs  
Temperature Control Systems.  
Business Machines  
Medical Equipment  
Uninterrupted Power Supplies (UPS).  
Communication  
CAPACITIVE LOADS: Caution must be used with low impedance  
capacitive loads to verify that the di/dt capabilities are not  
exceeded. The di/dt of a discharged capacitive load with out  
external limiting impedance can approach infinity. Zero voltage  
turn-on is a particularly valuable means of limiting di/dt with  
capacitive loads.  
Traffic Signals, etc.  
APPLICATION AND SELECTION CRITERIA FOR SOLID STATE  
RELAYS:  
The Chart below indicates the areas in which SSR's (Solid State Relays) or  
EMR (Electromechanical Relays) has better capabilities. (X) Indicates the  
Better choice.  
MOTORS: Specifically, motors frequently have severe inrush  
currents during starting and can impose unusual voltages during  
turnoff. The inrush currents connected to mechanical loads having  
high starting torque or inertia should be carefully determined to  
verify that they are within the surge capabilities of the SSR. A  
current shunt and Oscilloscope should be used to examine the  
duration of the inrush current. Motor starting may frequently  
reoccur at short intervals and the affect of repetitive inrush currents  
on the thermal operating point of an SSR must be considered.  
Check the motor operating current and locked rotor current versus  
the SSR motor rating. The possibility of abnormally stalled rotor  
conditions which draw much higher than normal currents should be  
considered. An extended stalled rotor condition may require an  
oversized SSR or fuse protection. The generated EMF of certain  
motors can require an SSR to have a blocking voltage greater than  
might be expected from steady state line voltage. The voltage  
applied to an SSR by a motor circuit during turnoff should be  
examined with an oscilloscope to verify hat the applied voltages  
are safely below the specified SSR blocking voltages. Otherwise  
lock-on or erratic turnoff of the motor may occur. Some motor  
circuits may require higher than normal blocking voltage, transient  
limiting devices, or other techniques to control the voltage which  
must be blocked by an SSR during deceleration or direction  
reversal.  
SSR  
X
EMR  
Long Life  
Temperature Cycling  
Shock and Vibration Resistant  
Immunity to False Operation due to Transients  
Generation of RFI, EMI  
Multipole  
Multithrow (SPDT)  
Size (includes Heat Sink) for Equivalent Load Handling  
Contact Bounce  
Arcless Switching  
Acoustic Noise  
X
X
X
X
X
X
X
X
X
X
X
Zero Voltage Switching  
Ease Of Diagnosing Malfunction  
IC Compatibility  
X
X
X
Immunity to Humidity, Salt Spray & Dirt  
LOAD CONSIDERATIONS  
A major portion of application problems with SSR's result from operating  
conditions which specific loads impose upon an SSR. The following types  
of loads point out the potential problems that can occur with SSR's.  
WEBSITE: www.magnecraft.com EMAIL:info@magnecraft.com FAX ON DEMAND 1-800/891-2957, DOCUMENT 100  
PAGE 94  
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