Motor Thermal Protection; Brake Connection; Earth Connection - Danfoss VLT 2800 Series Operating Instructions Manual

Motor thermal protection

The electronic thermal relay in UL-approved frequency
converters has received the UL-approval for single
motor protection, when parameter 128 Motor thermal
protection has been set for ETR Trip and parameter
105 Motor current, I has been programmed to the
M, N
rated motor current (see motor nameplate).

Brake connection

No. 81 82 Brake resistor
R- R+ terminals
The connection cable to the brake resistor must be
screened/armoured. Connect the screen to the metal
cabinet of the frequency converter and to the metal
cabinet of the brake resistor by means of cable clamps.
Dimension the cross-section of the brake cable to
match the brake torque.
See the Design Guide for dimensioning of brake resis-
tors.
NB!
Please note that voltages up to 850 V DC
occur on the terminals.

Earth connection

As leak current to the earth is higher than 3.5 mA, the
frequency converter must always be earthed accord-
ing to prevailing national and local regulations. To
guarantee that the earth cable has a good mechanical
connection to terminal 95, the cable cross section must
2
be at least 10 mm or 2 rated earth wires that are ter-
minated separately. To increase safety you can install
an RCD (Residual Current Device), which guarantees
that the frequency converter trips when leak current
becomes too high. See also RCD Application Note
MN.90.GX.02.
70
®
VLT 2800 Series
®
MG.27.A2.02 - VLT is a registered Danfoss trademark