The alternate power source can be used for peak load shaving, provided the above conditions are met. The use of the emergency generator to supply nonemergency loads ensures that the emergency generator will supply emergency power when it is needed. A portable or temporary alternate source shall be available whenever the emergency generator is out of service for major maintenance or repair.
According to the NEC Handbook, a major maintenance or repair procedure is one that keeps the generator set out of service for more than a few hours. Transfer Equipment A General. Transfer equipment, including automatic transfer switches, shall be automatic, identified for emergency use, and approved by the AHJ. Transfer equipment shall be designed and installed to prevent the inadvertent interconnection of normal and emergency sources of supply in any operation of the transfer equipment.
B Bypass Isolation Switches. Means can bypass and isolate the transfer equipment. C Automatic Transfer Switches.
Automatic transfer switches shall be electrically operated and mechanically held. D Use. Transfer equipment shall supply only emergency loads. Other loads shall not be supplied from the emergency system transfer switch. Multiple transfer switches are required where a single generator is used to supply emergency and other loads. Signals Audible and visual signal devices shall be provided, where practicable, for the following purposes.
A Derangement. To indicate derangement of the emergency source. B Carrying Load. To indicate that the battery is carrying load. C Not Functioning. To indicate that the battery charger is not functioning. D Ground Fault. To indicate a ground fault in solidly grounded wye emergency systems of more than V to ground and circuit-protective devices rated A or more. The sensor for the ground-fault signal devices shall be located at, or ahead of, the main system disconnecting means for the emergency source, and the maximum setting of the signal devices shall be for a ground-fault current of As.
Instructions on the course of action to be taken in event of indicated ground fault shall be located at or near the sensor location. Signs A Emergency Sources. A sign shall be placed at the service entrance equipment indicating type and location of on-site emergency power sources. Exception: A sign shall not be required for individual unit equipment as specified in Wiring, Emergency System A Identification.
All boxes and enclosures including transfer switches, generators, and power panels for emergency circuits shall be permanently marked so they will be readily identified as a component of an emergency circuit or system.
B Wiring. To ensure that any fault on the normal wiring circuits will not affect the performance of the emergency wiring or equipment, wiring from an emergency source shall be kept entirely independent of all other wiring, except as permitted for: 1 Wiring in transfer equipment enclosures.
Wiring of two or more emergency circuits supplied from the same source shall be permitted in the same raceway, cable, box, or cabinet. C Wiring Design and Location. A value of TRUE specifies a direct path load. Conventional and Direct Path Loads. Direct path loads must lock the table before the load can proceed.
TRUE — Direct path waits until it can get a lock on the table before proceeding with the load. The direct path API tries to lock the table multiple times and waits one second between attempts. The maximum number of attempts made is If the table cannot be locked after 30 attempts, then the direct path API returns the error that was generated when trying to lock the table.
Default: The same file name as the data file, but with an extension of. They are not bad records, they simply did not match any record-selection criteria specified in the control file, such as a WHEN clause for example. The directory parameter specifies a directory to which the discard file will be written. If the DISCARD parameter is specified with a directory but no file name, then the specified directory is used and the default is used for the name and the extension.
If multiple data files are being loaded and you are also specifying the DISCARD parameter, it is recommended that you specify only a directory for the discard file, not a file name. A discard file specified on the command line becomes the discard file associated with the first INFILE statement if there is one in the control file.
If the discard file is also specified in the control file, then the command-line value overrides it. If a discard file with that name already exists, then it is either overwritten or a new version is created, depending on your operating system.
Assume that you are loading a data file named employees. The following example supplies only a directory name so the name of the discard file will be employees. Setting LOB columns for which there is no data available to NULL negates the need to do this through post-processing after the data is loaded. Any data inserted up to that point is committed.
To specify that all errors be allowed, use a very high number. Therefore, multitable loads do not terminate immediately if errors exceed the error limit. The following example specifies a maximum of 25 insert errors for the load. After that, the load is terminated. It means the load is performed using either conventional or direct path mode.
These SQL statements can be edited and customized. However, if any of the SQL statements returns an error, then the attempt to load stops. Statements are placed in the log file as they are executed. This means that if a SQL statement returns an error, then the remaining SQL statements required for the load will not be placed in the log file. The results of doing the load this way will be different than if the load were done with conventional or direct path.
Note that the external table option uses directory objects in the database to indicate where all input data files are stored and to indicate where output files, such as bad files and discard files, are created.
You must have READ access to the directory objects containing the data files, and you must have WRITE access to the directory objects where the output files are created.
All files in the external table must be identified as being in a directory object. If you do not have privileges to create new directory objects, then the operation fails. Extract those SQL statements and change references to directory objects to be the directory object that you have privileges to access.
Then, execute those SQL statements. Creates a table in the database that describes all fields in the input data file that will be loaded into any table. This is because the field names may not be unique across the different tables in the control file.
External Tables Concepts. Built-in functions and SQL strings cannot be used for object elements when you insert data into a database table from an external table.
The FILE parameter specifies the database file from which to allocate extents. To test that all parameters you have specified for the load are set correctly, use the LOAD parameter to specify a limited number of records rather than loading all records. No error occurs if fewer than the maximum number of records are found. For external tables method loads, only successfully loaded records are counted toward the total. So if there are 15 records in the input data file and records 2 and 4 are bad, then the following records are loaded into the table, for a total of 10 records - 1, 3, 5, 6, 7, 8, 9, 10, 11, and For conventional and direct path loads, both successful and unsuccessful load attempts are counted toward the total.
So if there are 15 records in the input data file and records 2 and 4 are bad, then only the following 8 records are actually loaded into the table - 1, 3, 5, 6, 7, 8, 9, and If you specify the LOG parameter, then you must supply a directory name, or a file name, or both. The following example creates a log file named emp1. The extension. Allows stream building on the client system to be done in parallel with stream loading on the server system.
To use multithreading between two single-CPU systems, you must enable multithreading; it will not be on by default. Multithreading functionality is operating system-dependent. Not all operating systems support multithreading. The following example enables multithreading on a single-CPU system. On a multiple-CPU system it is enabled by default. This is the default behavior.
For example, to create an absolute symbol whose address is the last byte of an output section named. For instance, the sizes of sections cannot be known until after allocation, so assignments dependent upon these are not performed until after allocation. If the result of an expression is required, but the value is not available, then an error results. In some cases, it is desirable for a linker script to define a symbol only if it is referenced, and only if it is not defined by any object included in the link.
The command language includes a number of built-in functions for use in link script expressions. Primarily useful to assign an absolute value to a symbol within a section definition, where symbol values are normally section-relative. ADDR section Return the absolute address of the named section.
Your script must previously have defined the location of that section. This is equivalent to. As an example, to align the output. The second use simply defines the value of a variable. You can use this function to provide default values for symbols. For example, the following command-file fragment shows how to set a global symbol begin to the first location in the. You can use this number as the start address of the first section, if you choose, to facilitate paging.
MAX exp1 , exp2 Returns the maximum of exp1 and exp2. MIN exp1 , exp2 Returns the minimum of exp1 and exp2. Semicolons Semicolons " ; " are required in the following places. In all other places they can appear for aesthetic reasons but are otherwise ignored.
The linker's default configuration permits allocation of all available memory. By using it carefully, you can describe which memory regions may be used by the linker, and which memory regions it must avoid. The linker does not shuffle sections to fit into the available regions, but does move the requested sections into the correct regions and issue errors when the regions become too full.
A command file may contain at most one use of the MEMORY command; however, you can define as many blocks of memory within it as you wish. Any symbol name may be used.
The region names are stored in a separate name space, and will not conflict with symbols, file names or section names. Use distinct names to specify multiple regions. If you omit the attribute list, you may omit the parentheses around it as well.
It is an expression that must evaluate to a constant before memory allocation is performed. For example, to specify that memory has two regions available for allocation--one starting at 0 for kilobytes, and the other starting at 0x for four megabytes. The rom memory region will get all sections without an explicit memory register that are either read-only or contain code, while the ram memory region will get the sections. If the combined output sections directed to a region are too big for the region, the linker will issue an error message.
The SECTIONS command controls exactly where input sections are placed into output sections, their order in the output file, and to which output sections they are allocated.
They are permitted here as well for your convenience in reading the script, so that symbols and the entry point can be defined at meaningful points in your output-file layout. If you do not use a SECTIONS command, the linker places each input section into an identically named output section in the order that the sections are first encountered in the input files.
If all input sections are present in the first file, for example, the order of sections in the output file will match the order in the first input file. The most frequently used statement in the SECTIONS command is the section definition , which specifies the properties of an output section: its location, alignment, contents, fill pattern, and target memory region. The whitespace around secname is required, so that the section name is unambiguous.
The other whitespace shown is optional. In formats which only support a limited number of sections, such as a. If the output format supports any number of sections, but with numbers and not names as is the case for Oasys , the name should be supplied as a quoted numeric string. A section name may consist of any sequence of characters, but any name which does not conform to the standard ld symbol name syntax must be quoted. See section Symbol Names. The linker will not create output sections which do not have any contents.
This is for convenience when referring to input sections that may or may not exist. For example,. In a section definition, you can specify the contents of an output section by listing particular input files, by listing particular input-file sections, or by a combination of the two. You can also place arbitrary data in the section, and define symbols relative to the beginning of the section. The contents of a section definition may include any of the following kinds of statement.
You can include as many of these as you like in a single section definition, separated from one another by whitespace. In any place where you may use a specific file or section name, you may also use a wildcard pattern. The linker handles wildcards much as the Unix shell does.
Wildcards only match files which are explicitly specified on the command line. The linker does not search directories to expand wildcards. However, if you specify a simple file name--a name with no wildcard characters--in a linker script, and the file name is not also specified on the command line, the linker will attempt to open the file as though it appeared on the command line.
In the following example, the command script arranges the output file into three consecutive sections, named. The following example reads all of the sections from file all. All of section. All of the remaining.
This example shows how wildcard patterns might be used to partition files. For all files beginning with an upper case character, the. DATA ; for all other files, the. The foregoing statements arrange, in your output file, data originating from your input files.
You can also place data directly in an output section from the link command script. Most of these additional statements involve expressions see section Expressions. Although these statements are shown separately here for ease of presentation, no such segregation is needed within a section definition in the SECTIONS command; you can intermix them freely with any of the statements we've just described.
Here is the full syntax of a section definition, including all the optional portions:. See section Section Definitions , and section Section Placement , for details on contents. Such impacts may go unnoticed by the loading team or in some cases is noticed but not reported. This may happen when the load team can see no apparent damage so consider reporting the impact unnecessary. Where the aircraft structure is formed using composite materials , all impacts must be reported. While evidence of significant damage to a metal structure is usually clearly visible, this is not necessarily true for composite materials.
Although the skin may appear to be undamaged, the core of a composite structure may have deformed or have been significantly weakened. SKYbrary Partners:. Safety knowledge contributed by:. Join SKYbrary If you wish to contribute or participate in the discussions about articles you are invited to join SKYbrary as a registered user.
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