Chapter 1
Load Control Relay Option Description
The Class 3000 load control relay is designed to operate at user-selected high
and low set points. This provides the user with the capability to reduce a
facility’s electrical (kilowatt) demand. By proper selection of the high kW limit,
the meter can be utilized to shave expensive electrical demand peaks by shed-
ding loads or by activating a local generator. The low kW limit set point will
allow the load to be re-established or will shut down the local generator.
A user-selectable timer (
ramp
) will delay relay activation to eliminate short-term
“nuisance” functioning, such as short-term motor start loads or compressor
burdens. Once activated, the relay has a second user-selectable timer (
hold
),
which keeps the relay active if the load falls below the low set point immediately
after operation. This is designed to prevent short time cycling such as could
occur in the control of an HVAC compressor, for example. The factory preset
for high-limit threshold is 30 seconds (adjustable range is 15-240 seconds); the
“hold” preset is 60 seconds (adjustable range is 60-2400 seconds).
The form “C” relay is mounted on the main meter board, which is located on
the back of the enclosure. It is capable of controlling 240VAC @ 3 amps. The
connection to the relay is through a three-screw terminal block (TB-5) located
next to the relay. The terminal block is removable to provide easy wiring of the
normally open or normally closed contacts. The relay option must be ordered
with the meter, as it is not field-installable.
All relay functions are programmed through four pushbuttons located on the
meter’s display board, which is mounted on the door of the enclosure.
High and low thresholds are shown on the Class 3000’s display screen during
programming. The display also shows the value of the two built-in timers.
During normal meter operation, the display provides the high and low
thresholds while also showing the “real-time” load in kilowatts (demand).
Installation should be performed by qualified personnel and only according to
all applicable electrical codes. E-Mon and its representatives assume no
responsibility for damage or injury resulting from the improper installation of
this meter.
3
2
Chapter 2
Load Control Relay Wiring
The Class 3000 load control relay is mounted on the main meter board inside the
enclosure and is capable of controlling 240VAC @ 3 amps.
Under no circum-
stances should voltage or current exceed these limits.
The connection to the
relay is through a three-screw terminal block (TB-5) located next to the relay. This
terminal block is removable to make wiring easier.
The relay is for pilot operation and should not be used for direct load control where
the load is above the 3-amp limit. However, it may be utilized for directly functioning
an alarm, again with precautions that the alarm load stays below the 3-amp rating.
Wiring
All wiring must be done in accordance with national and local electrical
codes, and only by qualified personnel.
Remove the three-screw terminal block from the circuit board by pulling it up and
away from the board. Connect the wires that are being used for the control/alarm
circuit to the terminal block. The control circuit wires should not be energized until
the installation is complete. The relay is a form “C” device and can be wired nor-
mally open (NO) or normally closed (NC), depending on desired functionality.
Re-install the terminal block onto the board by inserting it into the TB-5 socket.
Program the meter for the correct set points as described in Chapter 3.
TB-5
TB-5
R
NO
P
NC
....
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