Electrical Connections - Modine Manufacturing MPR Series Installation And Service Manual

ELECTRICAL CONNECTIONS

Electrical Connections
WARNING
1. Disconnect power supply before making wiring
connections or working on this equipment. Follow all
applicable safety procedures to prevent accidental
power up. Failure to do so can result in injury or death
from electrical shock or moving parts and may cause
equipment damage.
2. For units equipped for dual power supply sources, both
sources of power must be disconnected to prevent
electrical shock and equipment damage.
3. All appliances must be wired strictly in accordance with
the wiring diagram furnished with the appliance. Any
wiring different from the wiring diagram could result in a
hazard to persons and property.
4. Any original factory wiring that requires replacement
must be replaced with wiring material having a
temperature rating of at least 105°C.
5. Ensure that the supply voltage to the appliance, as
indicated on the serial plate, is not 5% greater than
rated voltage.
CAUTION
1. Ensure that the supply voltage to the appliance, as indicated
on the serial plate, is not 5% less than the rated voltage.
2. Do not reuse any mechanical or electrical component
which has been wet. Such components must be
replaced.
1. Installation of wiring must conform with local building
codes, or in the absence of local codes, with the National
Electric Code ANSI/NFPA 70 - Latest Edition. Unit must be
electrically grounded in conformance to this code. In
Canada, wiring must comply with CSA C22.1, Part 1,
Electrical Code.
2. Two copies of the job specific wiring diagram are provided
with each unit, one permanently affixed to the inside of the
door of the controls compartment and the other as a loose
copy with the literature packet that ships with the unit.
Refer to this diagram for all wiring connections.
3. Control wiring consists of both 24V analog control wiring
and low current digital control signal wiring. To avoid signal
interference, the two types should be run in separate
conduits. If run in the same conduit, the digital signal wiring
should be shielded at one end of the wiring run. Wiring
should be twisted, stranded, and shielded communication
wire.
4. The wire gauge must be sized according to the National
Electric Code or CSA code based on amp draw and length
of run. Refer to Table 9.1 for maximum wire lengths and
the number of wires that can be wired to each low voltage
terminal block based on the wire gauge being used.
Table 9.1 - 24V and Digital Control Wire Lengths
Minimum
Recommended
Wire Gauge
24V Control Wiring
22
20
18
16
14
roltage.
Maximum Distance from
Control Device to Unit
Digital Control Wiring
n/a 120
n/a 200
75 300
125 500
175 n/a
5. For field wiring to the factory terminal strip, the terminal
strip connections are designed to clamp down on the wires.
To properly connect the wires to the terminal strip:
• Push a small flat-head screwdriver into the square hole on
the terminal. Press firmly until the screwdriver hits the
back stop and opens the terminal (see Figure 9.1).
• Remove approximately 3/8" of insulation from the end of
the wire and push the stripped wire into the oval hole in
the terminal.
• Remove the screwdriver. Pull on the wire to make sure
that it is securely clamped in the terminal.
• Make sure that the terminal clamp is in contact with bare
wire (insulation removed).
Figure 9.1 - Terminal Strip Wiring
Oval Holes
for Wiring
(two rows each)
Square Holes
for Wire Release
(two rows each)
Terminal
Numbers
Test Probe
Points
6. Depending on the configuration of the unit controls, there
may be sensors that are field installed. Review the unit
ordered to verify that the sensors supplied match the
configuration of the unit. The following are sensors that
may be included for field installation:
• Supply Air Temperature Sensor
This sensor is required on all units and should be
mounted in the supply air ductwork downstream of the
unit. The sensor should be located at least 5 feet, but not
more than 20 feet downstream from the unit discharge.
• Space Temperature/Humidity Sensor
This sensor is required on all units that have space
temperature/humidity reset control. The sensor is to be
wall-mounted in the space at a height of approximately
5 feet from the floor.
• Building Pressure Sensor
This sensor is required on all units that have space
pressure control, either through modulating dampers or
variable frequency drive control on the supply air blower.
The sensor is to be mounted inside a control panel in the
space and includes two pressure taps. One pressure tap
is for outside atmospheric pressure reference, the other is
for sampling the space pressure.
• Duct Pressure Sensor
This sensor is required on all units that have duct
pressure control through variable frequency drive control
on the supply air blower. The sensor is to be mounted
with the sensing probe inserted into the supply duct. The
atmospheric pressure sampling tap is left open.
MCP15-500.9
9