5 two-hand control – Banner SC22-3E Safety Controller with Ethernet User Manual
Page 100
cause the response time to increase based on the debounce time.
In this situation, the response time could be longer than specified,
based on the (selected) debounce time, see section
Complementary (PNP device): This circuit can meet ISO
13849-1 category 2, 3, or 4 requirements depending on the safety
rating and the installation of the device. This circuit can detect a
short circuit between channels. In the actuated condition (e.g., S1
OFF/S2 ON as shown), a short across the closed contact can
cause the response time to increase based on the debounce time.
In this situation, the response time could be longer than specified,
based on the (selected) debounce time, see section
ON
OFF
S1
S2
10.5 Two-Hand Control
The Safety Controller may be used as an initiation device for most powered machinery when machine cycling is controlled by a
machine operator.
Using a two-hand control system makes the operator, in effect, a “hostage” while the hazard is present, thus limiting or preventing expo-
sure to the hazard. The two-hand control actuators must be located so that hazardous motion is completed or stopped before the opera-
tor can release one or both of the buttons and reach the hazard (see section
10.5.1 Two-Hand Control Separation (Safety) Distance
on
page 101).
The Safety Controller safety inputs used to monitor the actuation of the hand controls for two-hand control comply with the functionality of
Type III requirements of IEC60204-1 and ISO 13851 (EN 574) and the requirements of ANSI NFPA79 and ANSI B11.19 for two-hand
control, which include:
• Synchronous (simultaneous) actuation by both hands within a 500 ms time frame
• Where this time limit is exceeded, both hand controls must be released before operation is initiated
• Continuous actuation during hazardous condition
• Cessation of hazardous condition if either hand control was released
• Release and re-actuation of both hand controls to re-initiate the hazardous motion or condition (i.e., “anti-tie down”)
• The appropriate performance level of the safety-related function (e.g., Control Reliability, Category/Performance level, or appropriate
regulation and standard, or SIL) as determined by a risk assessment
See section
on page 36 for more information.
WARNING: . . . Point-of-Operation Guarding
When properly installed, a two-hand control device provides protection only for the hands of the machine operator. It may be
necessary to install additional safeguarding, such as safety light screens, additional two-hand controls, and/or hard
guards, to protect all individuals from hazardous machinery.
Failure to properly guard hazardous machinery can result in a dangerous condition which could lead to serious in-
jury or death.
CAUTION: . . . Hand Controls
The environment in which hand controls are installed must not adversely affect the means of actuation. Severe con-
tamination or other environmental influences may cause slow response or false ON conditions of mechanical or ergonomic
buttons. This may result in exposure to a hazard.
The level of safety achieved (e.g., ISO 13849-1 Category) depend in part on the circuit type selected. See section
SC22-3/-3E Safety Controller Instruction Manual
100
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