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Chapter 5—Input/Output Capabilities 63230-300-212
Calculating the Watthour-Per-Pulse Value April 2001
© 2001 Schneider Electric All Rights Reserved
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This section shows an example of how to calculate kilowatthours per pulse.
To calculate this value, first determine the highest kW value you can expect
and the required pulse rate. In this example, the following assumptions are
made:
• The metered load should not exceed 1600 kW.
• About two KYZ pulses per second should occur at full scale.
Step 1: Convert 1600 kW load into kWh/second.
Step 2: Calculate the kWh required per pulse.
Step 3: Round to nearest hundreth, since the circuit monitor only accepts
0.01 kWh increments.
Summary:
• 3-wire application—0.22 kWh/pulse provides approximately 2 pulses per
second at full scale.
• 2-wire application—0.11 kWh/pulse provides approximately 2 pulses per
second at full scale. (To convert to the kWh/pulse required for a 2-wire
application, divide Ke by 2. This is necessary because the circuit monitor
Form C relay generates two pulses—KY and KZ—for every pulse that is
counted.)
CALCULATING THE
KILOWATTHOUR-PER-PULSE
VALUE
1 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