Power Systems Protection and Relaying code numbers

In North America protective relays are generally referred to by standard device numbers. Letters
are sometimes added to specify the application (IEEE Standard C37.2-2008).


Following the ANSI/IEEE Standard Device Numbers (the more commonly used ones are in bold)

1 - Master Element
2 - Time Delay Starting or Closing Relay
3 - Checking or Interlocking Relay
4 - Master Contactor
5 - Stopping Device
6 - Starting Circuit Breaker
7 – Rate of Change Relay
8 - Control Power Disconnecting Device
9 - Reversing Device
10 - Unit Sequence Switch
11 – Multifunction Device
12 - Overspeed Device
13 - Synchronous-speed Device
14 - Underspeed Device
15 - Speed or Frequency-Matching Device
16 – Data Communications Device
20 - Elect. operated valve (solenoid valve)
21 - Distance Relay
23 - Temperature Control Device
24 – Volts per Hertz Relay
25 - Synchronizing or Synchronism-Check Device
26 - Apparatus Thermal Device
27 - Undervoltage Relay
30 - Annunciator Relay
32 - Directional Power Relay
36 - Polarity or Polarizing Voltage Devices
37 - Undercurrent or Underpower Relay
38 - Bearing Protective Device
39 - Mechanical Conduction Monitor
40 –Field (over/under excitation) Relay
41 - Field Circuit Breaker
42 - Running Circuit Breaker
43 - Manual Transfer or Selector Device
46 – Rev. phase or Phase-Bal. Current Relay
47 - Phase-Seq. or Phase-Bal. Voltage Relay
48 - Incomplete-Sequence Relay
49 - Machine or Transformer Thermal Relay
50 - Instantaneous Overcurrent
51 - AC Time Overcurrent Relay
52 - AC Circuit Breaker
53 – Field Excitation Relay
55 - Power Factor Relay
56 - Field Application Relay
59 - Overvoltage Relay
60 - Voltage or Current Balance Relay
62 - Time-Delay Stopping or Opening Relay
63 - Pressure Switch
64 - Ground Detector Relay
65 - Governor
66 – Notching or jogging device
67 - AC Directional Overcurrent Relay
68 - Blocking or “out of step” Relay
69 - Permissive Control Device
74 - Alarm Relay
75 - Position Changing Mechanism
76 - DC Overcurrent Relay
78 - Phase-Angle Measuring Relay
79 - AC-Reclosing Relay
81 - Frequency Relay
83 - Automatic Selective Control or Transfer Relay
84 - Operating Mechanism
85 – Pliot Communications, Carrier or Pilot-Wire Relay
86 - Lockout Relay
87 - Differential Protective Relay
89 - Line Switch
90 - Regulating Device
91 - Voltage Directional Relay
92 - Voltage and Power Directional Relay
94 - Tripping or Trip-Free Relay
B – Bus
F - Field
G – Ground or generator
N – Neutral
T – Transformer

Engine Cycle

a constant mass of gas, the operation of a heat engine is a repeating cycle and its PV diagram will be a closed figure. The idea of an engine cycle is illustrated below for one of the simplest kinds of cycles. If the cycle is operated clockwise on the diagram, the engine uses heat to do net work. If operated counterclockwise, it uses work to transport heat and is therefore acting as are frigerator or a heat pump.



Engine Cycle Analysis

1.

2.


3.

4.

Standard diesel engine cycle


The diesel internal combustion engine differs from the gasoline powered Otto cycle by using a higher compression of the fuel to ignite the fuel rather than using a spark plug ("compression ignition" rather than "spark ignition").
Air standard diesel engine cycle
In the diesel engine, air is compressed adiabatically with a compression ratio typically between 15 and 20. This compression raises the temperature to the ignition temperature of the fuel mixture which is formed by injecting fuel once the air is compressed.
The ideal air-standard cycle is modeled as a reversible adiabatic compression followed by a constant pressure combustion process, then an adiabatic expansion as a power stroke and an iso volumetric exhaust. A new air charge is taken in at the end of the exhaust, as indicated by the processes a-e-a on the diagram.
Since the compression and power strokes of this idealized cycle are adiabatic, the efficiency can be calculated from the constant pressure and constant volume processes. The input and output energies and the efficiency can be calculated from the temperatures and specific heats:
It is convenient to express this efficiency in terms of the compression ratio rC = V1/V2 and the expansion ratio rE = V1/V3. The efficiency can be written
and this can be rearranged to the form

The difference between TBN and TAN

TBN is total base number and TAN is total acid number. TBN is a measure of the reserve alkalinity or reserve acid neutralization remaining in the oil. TAN measure the increase of oil oxidation and build-up of corrosive acidic compounds. Engine manufacturers often recommend utilizing both tests to gain a more in depth understanding of oil condition and engine oil remaining protection. In utilizing both tests, the TBN will decrease over time and TAN will increase over time. The point where the two numbers meet or cross over can be considered the point where the oil can no longer provided adequate corrosive where protection.

TBN In Diesel Engine Oils

TBN is an important property of engine oils. The abstract definition is as follows;

“Total Base Number (TBN) is the quantity of acid, expressed in terms of the equivalent number of milligrams of potassium hydroxide that is required to neutralize all basic constituents present in 1 gram of sample (ASTM Designation D 974)”. But this tells us little about what TBN in an engine oil does, nor how much we need for effective engine oil performance and engine protection.

The detergent additive in an engine oil has two functions
• To control deposits in the hot parts of the engine such as the pistons and turbocharger bearings.
• To neutralize acidic products of combustion from the fuel that can cause corrosive wear.

Engine oil formulators have always matched the amount of TBN to the amount of sulfur in the fuel. Today Chevron manufactures engine oils with 70 TBN which are used in marine engines operating on 5% sulfur fuel. This is very high sulfur content, 50,000 parts per million. Diesel fuel in the US was approximately 2,500 to 3,000 ppm sulfur (the legal maximum for ASTM 2D fuel was 5000 ppm) until 1993, when EPA regulations required a reduction to a maximum limit of 500 ppm for on road use. Today all diesel fuel is limited to 15 ppm sulfur maximum (Ultra Low Sulfur Diesel, or ULSD).

With 3000 ppm sulfur diesel fuel, oil TBN in the range of 10 to 14 was common, with lower priced oils at approximately 8 TBN. Current engine oils for use with ULSD are around 8 to 9+. Clearly the need for high TBN does not exist with today’s ULSD fuels.

How is TBN measured? It is important to note there are several test methods for Total Base Number. The one used in product data sheets is generally ASTM D 2896. This method uses perchloric acid to neutralize the alkalinity in the oil and yields a slightly higher number than the test method used by the oil analysis labs. They generally use ASTM D 4739 and the acid used here is hydrochloric acid. This produces a number approximately 2 mg KOH/g LOWER than ASTM D 2896 for the same oil. Due to chemical interferences, this test method does not recognize all of the alkalinity that ASTM D 2796 sees.

Why are there two test methods? The oil manufacturers have typically used ASTM D 2896 and their labs are set up to handle perchloric acid, which is toxic and hard to handle. In addition ASTM D 2896 can measure both the “hard base” from metallic detergent as well as the “soft base” from organic, non- metallic ingredients. So it is a more accurate method. BUT, the production oil analysis labs prefer to use a safer and easier to use titration acid, namely hydrochloric acid. The tests can be run faster, more cost effectively and more safely.

How much TBN do we need to protect the engine? The old rule was to change the engine oil when 50% of the new oil TBN had been consumed. Because of the virtual absence of fuel sulfur today, much less is needed. Chevron now sets the TBN guidelines for all of its diesel engine oils as follows:

FOR ALL OILS when using ULSD
• Severity 1: 50%-44% of new oil TBN or 3.5 to 4
• Severity 2: 43%-36% of new oil TBN 3 48 to 2.9
• Severity 3: <35% of new oil TBN < 2.8 to 2
• Severity 4: less than 2 <2

Other parameters of engine oil are now more important to engine durability and extended service protection than TBN. These are parameters such as oxidation stability, wear control, effective soot dispersancy. A balanced oil has multiple performance abilities and TBN is only one of the performance measures that are important in today’s high performance engine oil.

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