Safe Torque Off (Sto); Additional Connections; Serial Communication; Mechanical Brake Control - Danfoss VLT FC 102 Operating Instructions Manual

Electrical Installation

4.8.5 Safe Torque Off (STO)

To run STO, additional wiring for the frequency converter is
required. Refer to VLT
Operating Instructions for further information.

4.9 Additional Connections

4.9.1 Serial Communication

4 4
RS485 is a 2-wire bus interface compatible with multi-drop
network topology, that is nodes can be connected as a
bus, or via drop cables from a common trunk line. A total
of 32 nodes can be connected to 1 network segment.
Repeaters divide networks.
NOTICE
Each repeater functions as a node within the segment in
which it is installed. Each node connected within a given
network must have a unique node address across all
segments.
Terminate each segment at both ends, using either the
termination switch (S801) of the frequency converters or a
biased termination resistor network. Always use screened
twisted pair (STP) cable for bus cabling, and always follow
good common installation practice.
Low-impedance ground connection of the screen at every
node is important, including at high frequencies. Thus,
connect a large surface of the screen to ground, for
example with a cable clamp or a conductive cable gland. It
may be necessary to apply potential-equalizing cables to
maintain the same ground potential throughout the
network, particularly in installations with long cables.
To prevent impedance mismatch, always use the same
type of cable throughout the entire network. When
connecting a motor to the frequency converters, always
use screened motor cable.
Cable
Impedance
Cable length
[m]
Table 4.10 Cable Recommendations
48
®
Frequency Converters Safe Torque Off
Screened twisted pair (STP)
120 Ω
Maximum 1200 (including drop lines)
Maximum 500 station-to-station
Danfoss A/S © 04/2015 All rights reserved.
®
VLT HVAC Drive FC 102 Low Harmonic Drive

4.9.2 Mechanical Brake Control

In hoisting/lowering applications, it is necessary to be
able to control an electro-mechanical brake:
•
•
•
•
•
If the frequency converter is in alarm mode or in an
overvoltage situation, the mechanical brake immediately
cuts in.
Control the brake using any relay output or
digital output (terminal 27 or 29).
Keep the output closed (voltage-free) as long as
the frequency converter is unable to support the
motor, due to the load being too heavy, for
example.
Select [32] Mechanical brake control in parameter
group 5-4* Relays for applications with an electro-
mechanical brake.
The brake is released when the motor current
exceeds the preset value in
parameter 2-20 Release Brake Current.
The brake engages when the output frequency is
less than the frequency set in
parameter 2-21 Activate Brake Speed [RPM] or
parameter 2-22 Activate Brake Speed [Hz], only if
the frequency converter completes a stop
command.
MG16I302