Danfoss MLM116 Application Manuallines page 16

Application Guidelines
Phase sequence and reverse
rotation protection
Voltage imbalance
16
FRCC.PC.035.A5.02
Electrical data, connections and wiring
Use a phase meter to establish the phase
orders and connect line phases L1, L2 and L3
to terminals T1, T2 and T3, respectively. The
compressor will only operate properly in a single
Compressor models MLM/MLZ116 are delivered
with an electronic module which provides
protection against phase reversal and phase
loss at start-up. Apply the recommended wiring
diagrams from section "Suggested wiring
diagram logic". The circuit should be thoroughly
checked in order to determine the cause of the
phase problem before re energizing the control
circuit.
The phase sequencing and phase loss monitoring
functions are active during a 5-sec window 1
second after compressor start-up (power on
L1-L2-L3).
Compressor
start
Phase monitoring
0 1 s
Phase sequence module logic
The operating voltage limits are shown in the
table section "Motor voltage". The voltage applied
to the motor terminals must lie within these
table limits during both start-up and normal
operations. The maximum allowable voltage
% voltage
imbalance =
Vavg = Mean voltage of phases 1, 2, 3.
V1-2 = Voltage between phases 1 and 2.
direction, and the motor is wound so that if the
connections are correct, the rotation will also be
correct.
Should one of these parameters be incorrect, the
relay would lock out (contact M1-M2 open). The
red led on the module will show the following
blink code:
In case of phase reverse error:
Appr. 1 second
In case of phase loss error:
Appr. 1 second
The lockout may be cancelled by resetting the
power mains (disconnect L-N) for approximately
5 seconds.
6 s
imbalance is 2%. Voltage imbalance causes high
amperage over one or several phases, which in
turn leads to overheating and possible motor
damage. Voltage imbalance is given by the
formula:
| Vavg - V1-2 | + | Vavg - V1-3 | + | Vavg - V2-3 |
2 x Vavg
V1-3 = Voltage between phases 1 and 3.
V2-3 = Voltage between phases 2 and 3.
Single compressors
x 100