Working with the MPG-2 (cont)
Bi-Directional Energy Flow (Signed Mode)
If you have energy flowing in both directions in the case of distributed energy resourses (solar, wind, etc), the MPG-2 can
provide both positive and negative pulses. This is known as the
Signed
mode, meaning that "kWh Delivered" (
from
the
utility
to
the customer) is positive or forward flow, and "kWh Received" (
from
the customer
to
the utility) is negative or
reverse flow.
The Pulse Value Setting is the same for both positive and negative values.
To enter the functional or operational mode into the MPG-2, use the Pulse Mode field. Select
Normal
to set the MPG-2
in the Normal mode. Hit "Send". Select
Signed
to set the MPG-2 in the Signed mode. Hit "Send". The serial link to the
MPG-2 will return "Signed". To read click on Read Values. The serial link will return the mode stored in the MPG-2. For
example, "Normal" will be returned for the Pulse Mode. Case does not matter.
Form C Signed mode - A positive energy value received from the meter is added to the positive Accumulated Energy
ReAER). Negative energy values received are ignored. Only Form C toggle pulses are generated on the KYZ
output for Positive energy flow. See Figure 3 below.
Form A Signed mode - A positive energy value received is added to the positive Accumulated Energy ReAER).
A negative energy value received is added to the negative Accumulated Energy Register(-AER). When either register
equals or exceeds the Pulse Value setting, a pulse of the corresponding sign is outputted on the correct line. Pulses in
this mode are Form A (2-wire) "Fixed" only. K-Y pulses are Positive pulses and K-Z pulses are negative pulses. They
share a common K terminal on the output. Set the pulse value with the Pulse Value field. Set the pulse width using the
Pulse Width field. See Figure 4 below.
T1
Figure 4: 2-Wire (FORM A) FIXED Output Operation
K-Y Out
Open
Closed
Open
Closed
K-Z Out
KY closure time
In Signed mode, with a Form A output mode selected, the K-Y output pulse represents
positive (or kWh delivered) energy; K-Z output pulse represents negative (or kWh received)
energy.
(Positive)
(Negative)
Figure 3: 3-Wire (FORM C) TOGGLE Output Operation
K-Z Out
K-Y Out
Open
Open
Closed
Closed
Positive Energy Pulse Outputs Only
Positive and Negative Energy Pulse Outputs
In Signed mode, with a Form C output mode selected, the K-Y and K-Z output pulses
represent positive (or kWh delivered) energy; Negative (or kWh received) energy is ignored.
Positive Flow
Positive Flow
Negative Flow
Positive Flow
Positive Flow
Negative Flow
