Schneider Electric PM820, PM870 Fixed Pulse Output, Calculating the Kilowatthour-Per-Pulse Value

63230-500-225A2	PowerLogicTM Series 800 Power Meter
3/2011	Chapter 5—Input/Output Capabilities
	In Figure 5–3, the transitions are marked as 1 and 2. Each transition represents the time
	when the relay contact closes. Each time the relay transitions, the receiver counts a pulse.
	The power meter can deliver up to 12 pulses per second in a 2-wire application.

Fixed Pulse Output

Fixed pulse output mode generates a fixed duration pulse output that can be associated with kWh consumption. Figure 5–4shows the difference in pulse duration values when either TRANS mode or PULSE mode is selected. This mode selection is configured on the MAINT > IO > ADVAN menu.

Figure 5–4: Fixed-pulse output

TRANS & PULSE mode

Pulse Weight = 0.02kWHr/pulse

TRANS mode:

Counts = 4

Setting in ADV mode:

PULSE mode (100ms): 100 msec 10, 25, 50, 100, 150, 200, 300, 500, 1000

Counts = 8

0.02kW 0.04kW 0.06kW 0.08kW 0.1kW 0.12kW 0.14kW 0.16kW

Calculating the Kilowatthour-Per-Pulse Value

The following example illustrates how to calculate kilowatthours per pulse (pulse weight). To calculate this value, first determine the highest kW value you can expect and the required pulse rate. Remember the maximum number of pulses is 8 per second.

In this example, the following conditions are set:

•The metered load should not exceed 1600 kW.

•About two KY pulses per second should normally occur. (If a higher load is reached, the number of pulses per second can increase and still stay within the set limits.)

Step 1: Convert 1600 kW load into kWh/second.

(1600 kW)(1 Hr) = 1600 kWh

(1600------------------------------kWh)	=		-----------------------X kWh
1 hour			1 second
------------------------------------(1600 kWh)		=	-----------------------X kWh
3600 seconds			1 second

X = 1600/3600 = 0.444 kWh/second

Step 2: Calculate the kWh required per pulse.

0.444 kWh/second

------------------------------------------------- = 0.222 kWh/pulse

2 pulses/second

Step 3: Adjust for the KY initiator (KY will give one pulse per two transitions of the relay).

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