Overcurrent Relay (OCR)
It operates when a certain value or greater of current flows through. There are two elements: overcurrent detection (known as a timing element) and short-circuit current detection (as an instantaneous element).
Earth Fault Overcurrent Relays (OCGR, GR)
It will operate when the ground fault current (zero-phase current) reaches a certain value or greater. When detecting a ground fault, a zero-phase current transformer (ZCT) detects the zero-phase current. It is desirable to use a ground fault directed relay (DGR) in a circuit with a large capacitance to ground, such as when a long cable length is due to a concern about a fault.
Overvoltage Relay (OVR)
Relays work when a voltage exceeds the desired value applied to the circuit and protects the equipment from overvoltages caused by generator failures, etc. In particular, it can be used in power purchase circuits in customers with serious voltages.
Undervoltage Relay (UVR)
A relay that operates when the voltage of a circuit drops below the planned value, is used to warn of voltage drops due to power failures or short circuits in loads, and is used to start a backup generator.
Earth Fault Overvoltage Relay (OVGR)
It is a type of relay that works by detecting the zero-phase voltage that occurs when a ground fault occurs on a distribution line. Zero-phase voltage, electric utility TD line and the ultra-high voltage to power reception in the case of the customer, through a broken triangle connected to the ground voltage transformer (EVT), the circuit of the three-level side of the high-voltage consumer who receives the voltage divider circuit by the grounding capacitor at home is detected by the capacitor type Zero Phase Voltage Detector (ZPD). OVGR is rarely used alone, but in combination with DGR.
Differential Relays (DFR)
It operates when the vector difference between the currents flowing into and out of the protection section exceeds a predetermined value. Under normal conditions, in the event of an accident outside the protective area, the CT secondary currents I 1 and I 2 will be in equilibrium and will not work, but in the event of an internal accident, the balance will be lost and the differential currents I 1 -I 2 will flow towards operation.
Ratio Differential Relays (RDFR)
In differential relays, due to the saturation characteristics of CT, faults can be caused when error currents flow through. Therefore, an operating coil and a suppression coil are arranged in the differential circuit section, and the operation is performed when the ratio of the current of the operating coil to the current of the suppression coil exceeds a predetermined value. Differential and ratiometric relays are used to protect transformers, generators, and busbars.
Ground Fault Directional Relay (DGR)
The zero-phase voltage and zero-phase current determine the direction of the ground fault and operate. If the DGR is installed in a distribution substation with multiple feeders, the zero-phase current is sensed by the secondary-side current of the ZCT, the zero-phase voltage is sensed by the transformer that is grounded, and the phase relationship is to selectively cut the grounded distribution line.
Short Circuit Relay (DSR)
The combination of line voltage and phase current determines the direction of the short-circuit location. It is a relay that operates by selecting a faulty part of the loop system or a system with a power supply on both sides that is difficult to detect by an overcurrent relay.
Distance Relay (DR)
Distance relays take voltage and current as inputs and operate when the ratio of voltage and current falls below a predetermined value. This ratio is known as the impedance seen by the repeater and is also known as the distance relay because this impedance is an electrical measure of the distance of the transmission line.
Underfrequency Relay (UFR)
It will operate when the frequency drops below the commercial frequency (50/60Hz). It is mainly used in generator circuits.
Overfrequency Relays (OFR)
It will run when the frequency exceeds the commercial frequency (50/60Hz). It is mainly used in generator circuits.
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Siemens APT Relays – The difference between AC relays and DC relays
1. Structural characteristics of AC relays
The coil of the AC relay is shorter, and the wire diameter is thicker, mainly because the coil is passed through the alternating current, the reactance is larger, and the thick wire diameter can reduce the internal resistance and reduce the heat generation.
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Siemens APT transformer - the use of voltage transformer and precautions
The voltage transformer output is usually 100V
1. The working impedance in the secondary circuit of the voltage transformer should not be too small to avoid overload operation.
2 Before connecting the circuit, the polarity of the voltage transformer should be verified.
3 After connecting the circuit, the secondary coil should be reliably grounded, ...
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Siemens APT Relays - Selection Method for Solid State Relays
1. When selecting the solid-state relay used in the printed circuit board with small current specifications, because the lead terminal is made of high thermal conductivity material, the soldering should be carried out under the condition that the temperature is less than 250 °C and the time is less than 10S.
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Siemens APT warning light - the role of LED warning light in life
LED warning light function
1. The luminous method selection items are: solid light, shiny, burst flash, constant/shiny mix.
2. The installation base is: L rod, straight rod, folding, and barrel type.
Effect of LED warning light_Effect in different scenes
1. Construction unit
On the road ...
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Siemens APT limit switch - wiring method of limit switch
1. First of all, there is a general understanding of the knowledge of the limit switch, which is usually composed of a shell, an interconnection system and an operating head.
2. First of all, the limit switch should be set to the desired location, and then connected, in addition, it is necessary to figure out the meaning of different letters, such as NC for the long ...
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Siemens APT Relays – classified by their operating principle or structural characteristics
(1) Electromagnetic relay: an electrical relay that works by using the suction force generated by the current in the input circuit between the electromagnet core and the armature.
(2) Solid relay: refers to a kind of relay in which electronic components perform their functions without mechanical motion components, and the input and output are isolated.
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Siemens APT Relays – Classified by relay form factor
(1) Miniature relay: the longest side of the relay is not more than 10 mm.
(2) Ultra-miniature relay: the longest side size is greater than 10 mm, but not more than 25 mm.
(3) Small miniature relay: the longest side size is greater than 25 mm, but not large...
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Siemens APT - ALS series limit switch FAQ
1. What are the installation methods of ALS limit switches?
Usually the limit switch is divided into front of the board installation or board back installation, all of which are installed by screws.
2. What are the different modes of limit switch action?
According to the action mode of the limit switch head, it is divided into ...
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Siemens APT Relays – The working principle of zero-crossing AC solid state relays
1. Working process:
AC zero-crossing solid state relays have the characteristic of turning on when the voltage crosses zero and turns off when the load current crosses zero.
Circuit diagrams, dimensions and drawings of zero-crossing AC solid state relays
When the optocoupler OPT is turned off (i.e. there is no input signal at the control end of the OPT ...
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Siemens APT current transformer - how to see the multiple of the current transformer
1. Most of the multiple values can be seen from the nameplate attached to the instrument, which will show the style of the value/value, which can be known by dividing the previous value by dividing the back value when calculating the standard core-piercing turns. If the actual number of turns of the grommet does not conform to the standard, then the multiple should be ...
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Siemens APT Relays - a detailed introduction to the classification of relays
Classified according to the working principle or structural characteristics of relays:
1) Electromagnetic relay: an electrical relay that works by using the suction force generated by the current in the input circuit between the electromagnet core and the armature.
2) Solid state relay: refers to the electronic components that perform their functions without mechanical ...
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Siemens APT Relays – What should I pay attention to when selecting relays?
1. When selecting a relay, it is necessary to understand the load and type of its contact, because the contact method of the relay of the same model is different, with multiple groups of contacts and single group contacts. When selecting a relay, you can choose the type of contact.
2. And in the peach ...
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Siemens APT current transformer – the basis for whether the current transformer is damaged or the measurement is inaccurate
1. The inspection basis for whether the current transformer is damaged:
1. The basis for checking whether the polarity is damaged:
The primary winding of the current transformer is marked P1 and P2, and the secondary winding is marked as S1 and S2. If P1 and S1 are the same name, then this sign is called reduced polarity. Primary current from P1 ...
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Siemens APT Pushbutton Switches – How Many Types of Pushbutton Switches Are There?
There are several types of pushbutton switches:
Pushbutton switches can be classified according to the way they are protected and how they are operated. It can be divided into open type and protected type, as well as waterproof type and anti-corrosion type, etc. And explosion-proof, knob-type, key-type, emergency-type, are also its ...
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Siemens APT Relays – The Cause of Solid State Relays Burnout
1. Poor design (low margin of voltage or current reservation during selection, insufficient heat dissipation conditions, etc.).
2. The fuse is too large or the fast fuse is not used as required.
3. The radiator is full of dust or the cooling fan fails.
4. Solid State Relay ...
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Siemens APT Relays – Classified by relay load
(1) Micro-power relay: when the contact open circuit voltage is DC 28V, the (resistivity) is 0.1A, 0.2A relay.
(2) Weak power relay: when the contact open circuit voltage is DC 28V, (resistivity) is 0.5A, 1A relay.
(3) Medium power relay ...
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TL series police lights frequently asked questions
1. How many light sources are there for the TL-70 police light?
There are 3 types, namely LED, incandescent and xenon.
2. What are the colors of the TL-70 police light?
There are 5 types, which are red, yellow, green, blue, and white.
3. What are the types of TL-70 police lights?
3 ...
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Siemens APT relay - common faults and solutions for high-voltage relays
1. Poor contact
Poor contact is one of the most common faults in high-voltage relays, which can lead to problems such as hot terminals ® and burned contacts. Workarounds include regularly checking terminals and set screws for loose and cleaning contact surfaces.
2. Excessive wear
At...
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Siemens APT Relays – Selection Principles for High Voltage Relays
1. Electrical parameter matching: The rated voltage and current of the high-voltage relay need to match the circuit demand, too small will lead to the failure of the switch, too large will waste the cost.
2. Mechanical parameter adaptation: the external dimensions, pin arrangement and wiring mode of the high-voltage relay need to be adapted to the actual installation ring.
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Siemens APT Relays – The difference between solid state relays and intermediate relays
First, the solid-state relay has no contacts and coils in the structure, which can be opened and closed at a high frequency and will not produce sparks, and has a long service life;
Second, the intermediate relay is generally only used for the control loop, and cannot work with load, and will make a "pop" sound when it is sucked in;
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