AS-i Bus
Insulation Control Relay for AS-i Bus
© 2000 Schneider Electric All Rights Reserved
62
03/00
General
The RM0PAS101 insulation control relay detects and signals any ground fault
on either of the 2 polarities of an AS-i bus cable. It takes into account any
input/output ground faults of PNP intelligent splitter boxes (not isolated from
the bus).
Used in conjunction with the impedance adaptor LA9RM401 on the supply,
the RM0PAS101 insulation relay also detects faulty ground connections to
the relay itself and/or to the AS-i supply.
Operating Principle
The RM0PAS101 insulation control relay is supplied directly from the AS-i
bus. In the event of a fault, 1 of 2 output contacts allows breaking of the
supply to the actuators while the other can be used to signal the fault to a
PLC. In addition, the RM0PAS101 insulation control relay inhibits bus
communication in the event of a fault, in order to activate the watchdog
functions of the connected slaves.
Resetting, after rectification of fault and testing, can be performed by either
using the buttons on the front left-hand side of the relay, or by applying a
+ 24 V signal to the inputs on the terminal block (control by PLC output).
• Operation with no fault present
On power-up of the AS-i bus, the insulation control relay measures the
insulation resistance between each of the AS-i bus polarities (AS-i (+) and
AS-i (–)) and the ground terminal, and compares it to a value on the order
of 40 kΩ. If each resistance is higher than this value, the output relay
energizes and the “OK” LED illuminates.
• Appearance of a fault
Should one or both of the resistances measured (R
AS-i (+)/Ground
and/or
R
AS-i (–)/Ground
) fall below approximately 40 kΩ, or in the event of a fault in
the ground connection to the RM0PAS101 insulation control relay:
— The data exchanges on the AS-i bus are inhibited which, in turn,
triggers an alarm at the AS-i bus master within 5 ms.
— The output relay contacts open.
— The polarity on which the fault is detected is signalled by the
illumination of one or two LEDs (FAULT + or/and FAULT –), located on
the front left-hand side of the relay.
• Fault memory
The contacts remain open and the “Fault” LED stays on, even if the fault
disappears, unless the supply to the AS-i (+) and AS-i (–) terminals is
broken. If this occurs, the relay resets itself when the supply is restored,
providing the fault has disappeared, and the output relay contacts re-
close.
• Resetting
As soon as the fault is eliminated, the relay must be reset which, in turn,
closes the output relay contacts and extinguishes the associated “Fault”
LED. Two methods of resetting are possible:
— Locally, by pressing the RESET button.
— Remotely, by a change of state of the signal between terminals S1 and
S2 (see function diagram on the next page) lasting more than 30 ms.
This input must be permanently maintained at the high state when not
being used for resetting.
105
108
104
101
1
201
301
204
205
206
4
Q1
Q4
TEST
RESET
OK
FAULT+
FAULT
-
BUSBUS
1
2
3
4
6
7
7
5
Insulation control relay for AS-i bus:
1. Connections to the AS-i bus
2. TEST button
3. RESET button
4. Relay state LED indicator
5. I/O state indicators
6. Removable power supply terminal
7. Removable terminals
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