Schneider Electric PM870 Manual De Usuario

© 2011 Schneider Electric. All Rights Reserved.

The power meter calculates predicted demand for the end of the present interval for kW, 
kVAR, and kVA demand. This prediction takes into account the energy consumption thus 
far within the present (partial) interval and the present rate of consumption. The prediction 
is updated every second.

Figure 4–6 illustrates how a change in load can affect predicted demand for the interval.

In non-volatile memory, the power meter maintains a running maximum for the kWD, 
kVARD, and kVAD power values, called “peak demand.” The peak for each value is the 
highest average reading since the meter was last reset. The power meter also stores the 
date and time when the peak demand occurred. In addition to the peak demand, the power 
meter also stores the coinciding average 3-phase power factor. The average 3-phase 
power factor is defined as “demand kW/demand kVA” for the peak demand interval. 
Table 4–2 on page 30 lists the available peak demand readings from the power meter. 

You can reset peak demand values from the power meter display. From the Main Menu, 
select MAINT > RESET > DMD. You can also reset the values over the communications 
link by using software. 

The power meter also stores the peak demand during the last incremental energy interval. 
See “Energy Readings” on page 35 for more about incremental energy readings.

The power meter can perform any of the demand calculation methods, described earlier in 
this chapter, on up to 10 quantities that you choose using PowerLogic software. For generic 
demand, do the following: 

•

Select the demand calculation method (thermal, block interval, or synchronized).

•

Select the demand interval (from 5–60 minutes in 1–minute increments) and select 
the demand sub-interval (if applicable).

•

Select the quantities on which to perform the demand calculation. You must also 
select the units and scale factor for each quantity. 

For each quantity in the demand profile, the power meter stores four values:

•

Partial interval demand value 

•

Last completed demand interval value

•

Minimum values (date and time for each is also stored)

•

Peak demand value (date and time for each is also stored)

1:00

1:06

1:15

P

LS

D

1101

37

15-minute interval

Predicted demand if load is 
added during interval; 
predicted demand increases 
to reflect increase demand

Predicted demand if no load 
is added.

Time

Change in Load

Demand 
for last 
completed 
interval

Beginning 
of interval

Partial Interval 
Demand