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Revision 8.6
SECTION 2 : SYSTEM DESIGN
23
2.10. SELECTION OF INTERPOSING INPUT RELAYS
Every Thyromat installation makes use of input signals interposing relays. This is required to ensure that
the
10V DC Thyromat input signals are confined to the electrical panel. Such 10V DC remains
within the electrical panel environment.
External switching of directional as well as speed notch signals may then be supplied by the crane control
supply, which will control these interposing relays.
It is strongly recommended that the interposing relays have the following characteristics for optimum
system performance.
They must be hermetically sealed
This is a requirement due to most cranes operating under severe environmental conditions that
could include dust and/or corrosive gases
They must have a minimum contact burden of 5 mA / V
2.11. SELECTION OF INTERPOSING OUTPUT RELAYS
Where applicable, use interposing contactors between the relay outputs of the THYROMAT and the stator
/ rotor contactors.
Contactors can be used as single units or where necessary may be used in parallel. The rating of the
continuous supply current from the relay card is at a maximum of 2A, therefore the maximum continuous
allowable VA rating is 220 VA at 110 V and 440 VA at 220 Vac. This means that the consumption of each
contactor when closed may not exceed 50 VA (110 V system) or 100 VA (220 V system), leaving a small
margin to feed the brake contactor, which uses approximately ≤ 20 VA.
NOTE
In the event that interposing output relays are
required then the sum of the pull in and drop
out times of both the contactor and interposing
output relay should be taken into consideration
when setting up the phase shifter ON and OFF
time parameters. This is to ensure that the
switching under zero current remains true.
Example:
Drop out
Interposing relay:
LC1
– D0910
drop out time 12 ms
Associated contactor:
LC1 - F185
drop out time 50 ms
Combined drop out time
= 72 ms
Pull in
Interposing relay:
LC1
– D0910
pull in time
8 ms
Associated contactor:
LC1 - F185
pull in time
30 ms
Combined pull in time
= 38 ms
