(linking of DC intermediate circuit) or external 24
V DC is installed. Check that all voltage sources
have been disconnected and that the necessary
time has elapsed before commencing repair work.
For information about the discharge time, see .
NOTICE
When using the Safe Torque O, always follow the
instructions in VLT
®
Frequency Converters - Safe Torque
O Operating Instructions.
NOTICE
Control signals from, or internally within, the frequency
converter may in rare cases be activated in error, be
delayed, or fail to occur entirely. When used in situations
where safety is critical, for example, when controlling the
electromagnetic brake function of a hoist application,
these control signals must not be relied on exclusively.
NOTICE
Hazardous situations must be identied by the machine
builder/integrator who is responsible for taking
necessary preventive means into consideration. More
monitoring and protective devices may be included,
always according to valid national safety regulations, for
example, law on mechanical tools, regulations for the
prevention of accidents.
Crane, lifts, and hoists
The controlling of external brakes must always have a
redundant system. The frequency converter can in no
circumstances be the primary safety circuit. Comply with
relevant standards, for example:
Hoists and cranes: IEC 60204-32
Lifts: EN 81
Protection mode
Once a hardware limit on motor current or DC-link voltage
is exceeded, the frequency converter enters the protection
mode. Protection mode means a change of the PWM
modulation strategy and a low switching frequency to
minimise losses. This continues for 10 s after the last fault
and increases the reliability and the robustness of the
frequency converter while re-establishing full control of the
motor.
In hoist applications, protection mode is not usable
because the frequency converter is unable to leave this
mode again and therefore it extends the time before
activating the brake, which is not recommended.
Protection mode can be disabled by setting 14-26 Trip
Delay at Inverter Fault to zero, which means that the
frequency converter trips immediately if 1 of the hardware
limits is exceeded.
NOTICE
Disabling protection mode in hoisting applications
(14-26 Trip Delay at Inverter Fault=0) is recommended.
Introduction Programming Guide
MG11CE02 Danfoss A/S © 03/2015 All rights reserved. 9
1
1
To Next Page
Loading...
Need help?
General