Specifications

ManualsBrandsDanfoss ManualsHousehold Appliances102

Abbrev. Ref. Description

Cat. EN ISO

13849-1

Category, level “B, 1-4”

FIT Failure In Time: 1E-9 hours

HFT IEC 61508 Hardware Fault Tolerance: HFT = n

means, that n+1 faults could cause a

loss of the safety function

MTTFd EN ISO

13849-1

Mean Time To Failure - dangerous. Unit:

years

PFH IEC 61508 Probability of Dangerous Failures per

Hour. This value shall be considered if

the safety device is operated in high

demand (more often than once per

year) or continuous mode of operation,

where the frequency of demands for

operation made on a safety-related

system is greater than one per year

PFD IEC 61508 Average probability of failure on

demand, value used for low demand

operation.

PL EN ISO

13849-1

Discrete level used to specify the ability

of safety related parts of control

systems to perform a safety function

under foreseeable conditions. Levels a-e

SFF IEC 61508 Safe Failure Fraction [%] ; Percentage

part of safe failures and dangerous

detected failures of a safety function or

a subsystem related to all failures.

SIL IEC 61508 Safety Integrity Level

STO EN

61800-5-2

Safe Torque Off

SS1 EN 61800

-5-2

Safe Stop 1

Table 2.2 Abbreviations Related to Functional Safety

2.6.1

Terminal 37 Safe Torque Off Function

The FC 102 is available with Safe Torque Off functionality

via control terminal 37. Safe Torque Off disables the

control voltage of the power semiconductors of the

frequency converter output stage which in turn prevents

generating the voltage required to rotate the motor. When

the Safe Torque Off (T37) is activated, the frequency

converter issues an alarm, trips the unit, and coasts the

motor to a stop. Manual restart is required. The Safe

Torque Off function can be used for stopping the

frequency converter in emergency stop situations. In the

normal operating mode when Safe Torque Off is not

required, use the frequency converter’s regular stop

function instead. When automatic restart is used – the

requirements according to ISO 12100-2 paragraph 5.3.2.5

must be fulfilled.

Liability Conditions

It is the user’s responsibility to ensure personnel installing

and operating the Safe Torque Off function:

•

Read and understand the safety regulations

concerning health and safety/accident prevention

•

Understand the generic and safety guidelines

given in this description and the extended

description in the Design Guide

•

Have a good knowledge of the generic and safety

standards applicable to the specific application

Standards

Use of Safe Torque Off on terminal 37 requires that the

user satisfies all provisions for safety including relevant

laws, regulations and guidelines. The optional Safe Torque

Off function complies with the following standards.

IEC 60204-1: 2005 category 0 – uncontrolled stop

IEC 61508: 1998 SIL2

IEC 61800-5-2: 2007 – safe torque off (STO)

function

IEC 62061: 2005 SIL CL2

ISO 13849-1: 2006 Category 3 PL d

ISO 14118: 2000 (EN 1037) – prevention of

unexpected start-up

The information and instructions of the Operating

Instructions are not sufficient for a proper and safe use of

the Safe Torque Off functionality. The related information

and instructions of the relevant Design Guide must be

followed.

Protective Measures

•

Safety engineering systems may only be installed

and commissioned by qualified and skilled

personnel

•

The unit must be installed in an IP54 cabinet or

in an equivalent environment. In special

applications a higher IP degree may be necessary

•

The cable between terminal 37 and the external

safety device must be short circuit protected

according to ISO 13849-2 table D.4

•

If any external forces influence the motor axis

(e.g. suspended loads), additional measures (e.g.,

a safety holding brake) are required to eliminate

hazards

Introduction to VLT® HVAC D...

Design Guide

2 2