RST FRC-F Series, Manual

Page: 118 / 140

9.581.140-6
Page:
118
13.4 Function
The following circuit suggestions are to illustrate the safety problem and meets the safety requirements in
this form. Any implementation in practice must be checked for suitability for the relevant application and
subjected to a safety analysis.
As shown in both schematic circuit diagrams the frequency converter and the motor are coupled
directly. The two relays KSTO1 and KSTO2 replace the travel contactors typically used. Actuation is
performed by the higher-order lift controller. The voltage required for this is tapped at the end of the
safety circuit. The parallel-actuated (electronic) relay KGS enables the controller (GS) and ensures
that the frequency converter is switched off quickly in any type of emergency stop situations (including
inspection and return operations). This relay can also be replaced by an electronic variant, which is
recommended in particular in combination with operation of gearless, permanently excited
synchronous drives.The redundancy required according to EN 81-1 requires the use of two (parallel)
brake contactors.
The schematic diagram according to Figure 1ensures, in normal operation mode and emergency stop
situations (interruption of safety circuit), immediate activation of the mechanical brake if a brake
contactor (KBR1 and/or KBR2) fails.
Implementation of the schematic circuit diagram according to Figure 2
In the hazard analysis, it must be assessed, to what extent a fault of a brake contactor (KBR1/KBR2
and/or KBR_AC/KBR_DC) affects the safety of the lift system in emergency situations (interruption of
safety circuit). This is necessary in order to comply with the general safety requirements to be met by
lift systems and not specifically due to the fact that frequency inverters with integrated STO function
are used.
In both cases actuation of the brake contactors is performed by the higher-order controller. The
voltage required for this is tapped at the end of the safety circuit. Actuation of the two STO inputs
STO1 and STO2 of the frequency converter is done via corresponding make contacts of relays
KSTO1 and KSTO2. Via break contacts of these relays and the brake contactors, contactor drop-out
monitoring by the controller is guaranteed.
13.5 Requirements to be met by installation/components
For safety reasons, the design of the insulation must be based on degree of pollution 3 and
overvoltage category III according to DIN EN 61800-5-1.
If the control cables for signals STO1 and STO2 are outside of a closed electrical cabinet, protected
installation is required (shielded cable or separate installation in cable duct).
Forcibly guided contacts are not obligatory for relays KSTO1 and KSTO2. However, in this case,
contactor monitoring only has informative character as regards these relays.
Safe isolation between the coil and the contacts must be ensured.
The contacts of brake contactors KBR1/KBR2 resp. KBR_AC/KBR_DC must be forcibly guided. Safe
isolation must be ensured both between the coil and the contacts and between the individual contacts.
Safe isolation is guaranteed for the following values according to DIN EN 61800-5-1:
The air and creep distance between the coil and the contacts as well as between the individual
contacts must be at least 5.5 mm.
Electric strength between the coil and the contacts as well as between the individual contacts must be
at least 3000 V AC / 4240 V DC.