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10.1 Option -AS-, restart lock for personal safety
A frequently required application task is the protection of personnel against the restarting of drives.
This can not be achieved by an electronic inhibit, but must be implemented with mechanical ele
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ments (positively driven relay contacts).
To get round this problem, up to now either the main contactor in the mains supply line was
switched off, or another contactor was used to disconnect the motor from the servo amplifier.
The disadvantages of this method are :
— the DC bus link has to be charged up again at restart
— wear on the contacts of the contactors, caused by switching under load
— extensive wiring required, with additional switching components
The -AS- option avoids these disadvantages. A safety relay in the servo amplifier is activated either
by the PLC or manually. Positively driven contacts provide a safe disconnection of the servo ampli
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fier, the setpoint input of the servo amplifier is inhibited, and a signal is sent to the safety circuit.
The suggested circuits (ð p. 95) fulfills safety category 1 (EN 954-1) or category 3 with additional
safety relay (e.g. PNOZ of PILZ company).
Advantages of the -AS- option
— the DC bus link remains charged up, since the mains supply line remains active
— only low voltages are switched, so there is no contact wear
— very little wiring is required
— the functionality and the personnel safety when using the circuit recommendations
in this documentation have been approved by the Trade Liability Association.
Moving single axes or axis-groups in setting-up operation
In setting-up operation, people will frequently be within the danger zone of the machinery. Axes will
normally be moved under the control of permission switches. An additional switch-off of the unused
axes, by means of the restart lock, increases the safety margin and avoids the repeated switching
of main contactors or motor contactors.
Switching off grouped axes with separate working areas
Even when several SERVOSTAR 600 are operating off a common mains supply and DC bus link, it
is possible to set up groups for separate working areas. These groups can then be switched off sep
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arately for personnel safety.
10.1.1 Safety instructions
l
Observe "Use as directed" on page 92.
l
The monitoring contacts (KSO1/2) for each amplifier with an -AS- option must be looped
into the control circuit. This is vital, so that a malfunction of the internal safety relay or
a cable break can be recognized.
l
If the -AS- option is automatically activated by a control system (KSI1/2), then make
sure that the output of the control is monitored for possible malfunction. Can be used
to prevent a faulty output from activating the -AS- option while the motor is running.
l
It is vital to keep to the following functional sequence when the -AS- option is used:
1. Brake the drive in a controlled manner (speed setpoint = 0V)
2. When speed = 0 rpm, disable the servo amplifier (enable = 0V)
3. If there is a suspended load, apply an additional mechanical block to the drive
4. Activate the -AS- option
SERVOSTAR
®
601...620 Product Manual 91
Danaher Motion
07/2007 Expansions / Accessories