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This article will help you understand the differences between older S700 (S701-724) drives with single-channel STO and newer dual-channel STO S700 drives. 

Device EN 13849-1 EN 61800-5-2 PFHD (1/h) TM (Years)
Input STO-Enable PL d, Cat.3 SIL 2 1.50E-07 20
Device EN 13849-1 EN 61800-5-2 PFH(1/h) T(Years)
Input STO-Enable PL d, Cat.3 SIL 2  1.50E-07 20

There is no certification for the S601-620 drives according to EN 13849-1 or EN 62061.

Function Operation Mode ISO  13849-1 IEC 61508-2 PFH [1/h] TM [Years] SFF [%]
STO single channel PL d, CAT 2 SIL 2 1.88E-07 20 89
STO dual channel PL d, CAT 3 SIL 2 5.64E-09 20 87
STO dual channel with periodical testing PL d, CAT 4 SIL 3 5.64E-09 20 87
Structure STO ISO 13849-1 IEC 62061 PFH [1/h] SFF [%] TM (Years)
AKD-C + 1 x AKD-N global PL d, CAT 3 SIL 2 2.9E-08 97.08 20
AKD-C + 8 x AKD-N global PL d, CAT 3 SIL 2 2.9E-08 99.44 20
1 x AKD-N-DS local PL d, CAT 3 SIL 2 2.9E-08 97.12 20

STO, no safety card

Device S701-724 Operation mode EN 13849-1 EN 62061 PFH(1/h) T(Years) 
STO1/2-Enable single channel PLd, Cat.3 SIL CL2 7.05E-08 20
STO1-Enable+STO2-Enable dual channel PLd, Cat.3 SIL CL2 7.05E-08 20
STO1-Enable+STO2-Enable+STO-Status dual channel with periodic test PLe, Cat.4 SIL CL3 1.04E-09 20

With safety card S1-2/S2-2 and motor feedback

Motor feedback with unknown MTTF value

MTTF = 10 must be used in this case (according to the graduated process for estimation of MTTF in EN 13849-1:2008 chapt. 4.5.2). The motor encoder is already included in the characteristic data, so no further calculations need to be performed for the "Safe Actuator" subsystem. The subsystem is built from S700, safety card and motor feedback.

Device (feedback with unknown MTTF) EN 13849-1 EN 62061 PFH(1/h) T(Years) 
S700 with Safety card S1/S1-2 and unknown motor feedback PL d, Cat.3 SIL CL 2 1.26E-07* 20
S700 with Safety card S2/S2-2 and unknown motor feedback PL d, Cat.3 SIL CL 2 1.35E-07* 20

 * = depends on the MTTF value of the used feedback. The higher MTTF the smaller is PFHD . This has an influence to the complete system, even if PL and SIL classes don't change.

Motor feedback with MTTF value larger than 57

Most of the feedback systems, especially resolvers, have MTTF values larger than 57. The motor encoder is already included in the characteristic data, so no further calculations need to be performed for the "Safe Actuator" subsystem. The subsystem is built from S700, safety card and motor feedback.

Device (feedback with MTTF > 57) EN 13849-1 EN 62061 PFH(1/h) T(Years)
S700 with Safety card S1/S1-2 and Kollmorgen motor feedback PL e, Cat.4 SIL CL 3 2.37E-08* 20
S700 with Safety card S2/S2-2 and Kollmorgen motor feedback PL d, Cat.3 SIL CL 2 1.35E-07* 20

 * = depends on the MTTFD value of the used feedback. The higher MTTFD the smaller is PFHD . This has an influence to the complete system, even if PL and SIL classes don't change.

With safety card S1-2 and two feedback systems

In this case the system depends on the used feedback systems, therefore the system must be calculated individually. The given subsystem below is built from S700 and safety card S1-2, the feedback systems used by Kollmorgen are given as parts (see "Characteristic Data Feedback").

Device EN 13849-1 EN 62061 PFH(1/h) T(years) 
S700 with Safety card S1-2 PL e, Cat.4 SIL CL 3 1.19E-08 20

This is valid for drives with HWR >= 02.10.

Device S748-772 Operation mode EN 13849-1 EN 62061 PFH(1/h) T(Years) 
STO1/2-Enable single channel PLd, Cat.3 SIL CL2 7.05E-08 20
STO1-Enable+STO2-Enable dual channel PLd, Cat.3 SIL CL2 7.05E-08 20
STO1-Enable+STO1-Status+
STO2-Enable+STO2-Status
dual channel with periodic test PLe, Cat.4 SIL CL3 1.38E-09 20

If your S700 has two (2) STO safety circuits (drive P/N will be S7xxy2, where "xx" is the continuous current rating), please note:

1. Use the correct Installation Manual.  There is one (1) manual for the single channel STO and another for the dual STO.  You will need the dual channel STO manual.

A customer is wondering how quickly the AKD can enable the brake on the motor without line voltage. Considering the 24VDC bus voltage is still operating the STO. Imagine somebody goes inside the electrical panel where the AKD will be housed and accidently flips the circuit breakers killing the line voltage to the drive.

Assume the motors sees 25% of its rated current in a vertical application, will the AKD have enough stored energy to keep the load from dropping? Will the brakes be enabled as soon as the drive sees a drop in line voltage?

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