IEEE Std 1476-2000 pdf download

IEEE Std 1476-2000 pdf download.IEEE Standard for Passenger Train Auxiliary Power Systems lnterfaces.
4.2 Loads analysis
The following subclauses present the requirements for properly sizing the auxiliary power loads. These loads shall be compiled by the car builder and presented to the authority having jurisdiction and the suppliers.
N(JFE—The proper determination and sizing of the auxiliary loads is a very important step in the process of specifying auxiliary power supplies. If loads are specified too high by inclusion of conditions that realistically do not occur at the same time, the inverters and power supplies may be sized too large and result in unnecessaiily costly or heavy equipment. Conversely, if loads are underestimated or high transient start-up conditions are not accounted for, the auxiliary equipment may be undersized resulting in frequent turn-off, nuisance circuit breaker trips, or low reliability.
4.2.1 StatIc inverter ac loads
The ac loads shall be compiled to determine the load presented to the static inverter under the following conditions:
a) Quiescent design load during lay-up conditions
b) Full continuous operating load
c) Maximum simultaneous starting load
d) Sustained short-time heavy loads, such as HVAC compressor pull down load
For each of the above conditions, the information compiled for each of the load items addressed shall include the following:
— Nominal voltage, frequency and phases
— Power (kW) for each individual load
— Power factor of each individual load at nominal operating conditions
— Quantity of individual loads, comprising each load item, driven by static inverter
— Total connected power of load item (kW)
— Total kilovolt amperes presented by load item (kVA)
— Inrush current (high starting current) of load item
The compiled loads shall be prepared by the car builder and presented to the authority having jurisdiction and the suppliers. It shall be in the format shown in Table 2 and shall include all applicable loads and an estimate of the size of the loads. An example of a typical summary of ac loads is shown and described in Table A. 1.
4.2.2 Low-voltage dc loads
To compile and categorize the low-voltage dc loads, the failure management strategies (see NOTE below) shall first be developed, then the low-voltage dc loads categorized accordingly. The sequence of load-shedding shall be developed such that the loads are supported in harmony with the failure management strategies. The low-voltage dc loads shall be compiled to determine the load presented to the LVPS and the back-up battery as follows:
a) Tabulation of constant power loads, such as public address/intercom, radio, propulsion control, etc., that derive their primary power from the LVPS but have their own regulated power supply included within the units. This type of load presents two different current draws. The first current draw is that which occurs while the LVPS is active and the second is an increased current draw when the load is switched to back-up battery wherein the voltage source (now the battery) is approximately 15% lower voltage. This results in a corresponding increased current draw. As the battery voltage continues to drop during discharge, the current draw increases. These are the worst-case loads on the battery.
b) Tabulation of resistive loads, such as incandescent lamps, relay logic, etc., that do not have internal regulated supplies. This type of load also presents two different current draws. The first current draw is that associated with the LVPS providing nominal output voltage, and the second is a reduced current draw when the load is switched to the back-up battery wherein the voltage is approximately 15% lower, thus resulting in a corresponding decreased current draw. As the battery voltage continues to drop during discharge, the current draw correspondingly decreases.