Banner E-Stop ES-TN-14H5 Instruction Manual page 3

E-Stop Safety Modules with Adjustable Delay –
Key to Categories
• A Functional Stop Category (0, 1 or
2), per EN60204-1 and NFPA79, refers
to the type of stopping action required
by the guarded machine in question.
Some machines may be stopped safely,
immediately following a stop command
(removal of power); others, due to their
high speed, mass or momentum, would
run on following an immediate stop
command. These machines require power
to be provided to the guarded machine's
braking system for a specified delay time,
to effect a controlled stop.
Category 0 Stop: immediate removal of
power, uncontrolled stop
Category 1 Stop: controlled stop with
a delay before power is removed from
guarded machine
Category 2 Stop: controlled stop with
power left available to the guarded machine
actuators
• A Safety Category (B, 1, 2, 3 or 4), per
EN954-1, refers to "the performance of
a safety related part of a control system
(or circuit) with respect to the occurrence
of faults..." Of the many factors involved
when selecting an appropriate safety
category, hazard analysis, risk assessment
and risk reduction are among the most
important. The level of risk is based on
the severity of a potential harm and its
probability of occurring, which is used to
determine the appropriate performance of
a control system or circuit. Typically, as
described in Annex B of EN954-1, in cases
where serious injury is possible:
- Safety Category 2 would be selected
only if exposure to a hazard is
infrequent, and of a short duration.
- Safety Category 4 would be selected
if exposure to a hazard is frequent to
continuous, or if exposure is for a long
duration.
For more information, refer to standards
EN954-1, EN418, NFPA 79, EN60204-1 and
British Standard 5304:(1988).
Buy: www.ValinOnline.com | Phone 844-385-3099 | Email: CustomerService@valin.com
The purpose of an Emergency Stop Safety Module (E-Stop Safety Module) is to
increase the control reliability of an emergency stop circuit. As indicated in Figures 2
and 3, the E-Stop Safety Modules described in this document are designed to monitor
a 1-channel or 2-channel E-stop switch. A 2-channel E-stop switch has two electrically
isolated contacts.
ISO 13849-1 Safety Categories
Both contacts of a 2-channel E-stop switch are monitored by the Safety Module. If
either input is short-circuited, the Safety Module cannot be reset, and the controlled
machinery cannot be restarted, following actuation of the E-stop switch. Two-channel
E-stop switches used with this Safety Module are suitable for Safety Category 4
applications, per European Standard ISO 13849-1 (EN954-1), of which Category 4 is
the highest safety category.
Use of a 1-channel E-stop switch provides no input redundancy, and no ability for the
Safety Module to monitor for input short circuits. One-channel E-stop switches used
with this Safety Module are generally suitable only for Safety Category 2 applications,
per ISO 13849-1 (EN954-1).
IEC/EN60204-1 and NFPA79 Functional Stop Categories
In a functional Category 0 emergency stop circuit, the opening of either of the two
E-stop switch contacts (or the one contact, if configured to 1-channel) immediately
removes electrical power from the machine control elements, which react to stop
hazardous machine motion and/or other machine hazards. This redundancy of
stopping control offered by a two-pole E-stop switch is the first step towards control
reliability in an emergency stop circuit.
A functional stop Category 1 emergency stop circuit is a controlled stop with power
available to the machine actuators to achieve the stop and then removal of power when
the stop is achieved. When a Category 1 stop function is used, final removal of power
must be ensured by means of electromechanical switching devices.
Functional stop Category 1 stops are intended for use on machines where immediate
removal of power would not stop the machine immediately because its high speed,
high mass or momentum would cause the machine to run on. To stop such machines
quickly and safely, electro-mechanical or electrical brake systems like DC-injection
brakes or reverse current via the machine's actuators are commonly used.
The outputs of E-stop Safety Modules ES-TN-1H5 and -1H6 are two redundant
normally open immediate safety contacts (each of which is a series of two forced-
guided relay contacts, K1 and K2 in Figure 3), and two redundant normally open
delayed contacts (also each a series of two forced-guided relay contacts, K3 and K4).
The delayed contacts may be used in a functional stop Category 1 application.
Models ES-TN-14H5/-14H6
Overview