Demand - GE T60 Instruction Manual

CHAPTER 5: SETTINGS
— This setting selects the metering actual value that is to be recorded in Channel 1(16) of the data
DATA LOGGER CHNL 1(16)
log. The parameters available in a given relay are dependent on: the type of relay, the type and number of CT/VT hardware
modules installed, and the type and number of Analog Input hardware modules installed. Upon startup, the relay
automatically prepares the parameter list. A list of all possible analog metering actual value parameters is shown in
Appendix A: FlexAnalog Parameters. The parameter index number shown in any of the tables is used to expedite the
selection of the parameter on the relay display. It can be time-consuming to scan through the list of parameters via the
relay keypad/display—entering this number via the relay keypad causes the corresponding parameter to display.
— This display presents the total amount of time that the Data Logger can record the channels not
DATA LOGGER CONFIG
selected to "Off" without overwriting old data.

5.3.11 Demand

SETTINGS  PRODUCT SETUTP  DEMAND
 DEMAND

The relay measures current demand on each phase, and three-phase demand for real, reactive, and apparent power.
Current and Power methods can be chosen separately for the convenience of the user. Settings are provided to allow the
user to emulate common electrical utility demand measuring techniques, for statistical or control purposes. If the
is set to "Block Interval" and the
DEMAND METHOD
is assigned to any other FlexLogic operand, Method 2a is used as follows.
TRIGGER
The relay can be set to calculate demand by any of the following three methods.
5.3.11.1 Calculation method 1: Thermal exponential
This method emulates the action of an analog peak-recording thermal demand meter. The relay measures the quantity
(RMS current, real power, reactive power, or apparent power) on each phase every second and assumes that the circuit
quantity remains at this value until updated by the next measurement. It calculates the 'thermal demand equivalent'
based on the following equation:
where
d = demand value after applying input quantity for time t (in minutes)
D = input quantity (constant)
k = 2.3 / thermal 90% response time
The figure shows the 90% thermal response time characteristic of 15 minutes. A setpoint establishes the time to reach
90% of a steady-state value, just as the response time of an analog instrument. A steady state value applied for twice the
response time indicates 99% of the value.
T60 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CRNT DEMAND METHOD:

Thermal Exponential
POWER DEMAND METHOD:

Thermal Exponential
DEMAND INTERVAL:

15 MIN
DEMAND TRIGGER:

Off
DEMAND TRIGGER
Range: Thermal Exponential, Block Interval, Rolling
Demand
Range: Thermal Exponential, Block Interval, Rolling
Demand
Range: 5, 10, 15, 20, 30, 60 minutes
Range: FlexLogic operand
Note: for calculation using method 2a
is set to "Off," Method 2 is used as follows. If
PRODUCT SETUP
5
CRNT
DEMAND
Eq. 5-6
5-119