Chapter 5—Input/Output Capabilities 63230-300-212
Calculating the Watthour-Per-Pulse Va lue April 2001
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This sectionshows an example of how to calculate kilowatthours per pulse.
Tocalculate this value, first determinethe highest kW value you can expect
and the requiredpulse rate. In this example, the followingassumptions are
made:
•The metered load shouldnot exceed 1600 kW.
•About two KYZ pulsesper second should occur at full scale.
Step 1: Convert 1600 kW load into kWh/second.
Step 2: Calculate the kWh requiredper pulse.
Step 3: Round to nearest hundreth,since the circuit monitor only accepts
0.01 kWh increm ents.
Summary:
•3-wire application—0.22 kWh/pulseprovides approximately 2 pulses per
second at fullscale.
•2-wire application—0.11 kWh/pulseprovides approximately 2 pulses per
second at fullscale. (To convert to the kWh/pulse requiredfor a 2-wire
application,divide Ke by 2. This is necessary because the circuit monitor
Form C relaygenerates two pulses—KY and KZ—for every pulse that is
counted.)
CALCULATING THEKILOWATTHOUR-PER-PULSEVALU E1 hour
(1600 kW) (1 Hr) = 1600 kWh
(1600 kWh) = “X” kWh
(1600 kWh) = “X” kWh
X = 1600/3600 = 0.4444 kWh/second
3600 seconds
1 second
1 second
= 0.2222 kWh/pulse
0.4444 kWh/second
2 pulses/second
Ke = 0.22 kWh/pulse