Electrical data, connections and wiring
Three phase electrical
characteristics
Compressor model
LRA
MCC
Max. operating current Winding resistance
A
A
A
Ω
Motor voltage code 4
380-415 V/3 ph/50 Hz
MLZ/MLM116
175
39
35
0.914
Locked Rotor Amp value is the higher average
current as measured on mechanically blocked
compressor tested under nominal voltage. The
LRA value can be used as rough estimation for
the starting current. However in most cases, the
real starting current will be lower. A soft starter
can be applied to reduce starting current.
LRA (Locked rotor amp)
The MCC is the current at which the motor
protection trips under maximum load and
low voltage conditions. This MCC value is the
maximum at which the compressor can be
operated in transient conditions and out of
the application envelope. Above this value, the
electronic module will cut out the compressor to
protect the motor.
MCC (Maximum continuous
current)
The max. operating current is the current when
the compressor operates at maximum load
conditions and 10% below nominal voltage.
Max Oper. A can be used to select cables and
contactors.
In normal operation, the compressor current
consumption is always less than the Max Oper. A.
value.
Max. operating current
Winding resistance is the resistance between
phases at 25°C (resistance value +/- 7%).
Winding resistance is generally low and it
requires adapted tools for precise measurement.
Use a digital ohm meter, a "4 wires" method and
measure under stabilized ambient temperature.
Winding resistance varies strongly with winding
temperature. If the compressor is stabilized
at a different value than 25°C, the measured
resistance must be corrected using following
formula:
a + t
amb
R
tamb
= R
25°C
_______
a + t
25°C
t
25°C
: reference temperature = 25°C
t
amb
: temperature during measurement (°C)
R
25°C
: winding resistance at 25°C
R
amb
: winding resistance at tamb
Coefficient a = 234.5
Winding resistance
The inrush current for the Danfoss MLM/MLM116
compressors with motor code 4
380-415 V/3 ph/50 Hz can be reduced using
the Danfoss soft starter. MCI soft starters are
designed to reduce the starting current of
3-phase AC motors; they can reduce the inrush
current by up to 40%, thereby eliminating the
detrimental effects of high-starting torque surges
and costly demand charges from the resultant
current spike.
Danfoss MCI soft-start
controller
Upon starting, the controller gradually increases
the voltage supplied to the motor until full-line
voltage has been reached.
For MCI50M, all settings such as initial torque,
ramp-up time (less than 0.5 sec) and ramp-
down time are preset and do not require any
modification.
Initial torque
ramp-up
ramp-down
Time
U
Compressor model
Soft start reference
Ambient max. 40°C
Soft start reference
Ambient max. 55°C
MLM/MLZ116
MCI50CM
MCI50CM *
* by-pass contactor K1 is required
13
FRCC.PC.035.A5.02
Application Guidelines
Single compressors
