Demand - GE D60 Instruction Manual

CHAPTER 5: SETTINGS
— 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.

5.3.10 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.
5.3.10.1 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.
D60 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CRNT DEMAND METHOD:

Thermal Exponential
POWER DEMAND METHOD:

Thermal Exponential
DEMAND INTERVAL:

15 MIN
DEMAND TRIGGER:

Off
DEMAND TRIGGER
Figure 5-42: Thermal demand characteristic
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
CRNT
DEMAND
5
Eq. 5-6
5-103