14
Curtis 1207B Manual
SWITCHES AND OTHER HARDWARE
Keyswitch
The vehicle should have a master on/off switch to turn the system off when not
in use. The keyswitch provides logic power for the 1207B controller, coil cur
-
rent for the contactors, and shunt current (in compound motor applications).
The keyswitch must be capable of carrying these currents.
Main Contactor
A main contactor allows the 1207B controller to be disconnected from the bat-
tery. A heavy-duty single-pole, single-throw (SPST) contactor with silver-alloy
contacts is recommended, such as an Albright SW80 or SW180
.
After initial closing of the contacts, inrush currents flow as the controller’s
internal filter capacitors are charged. A 250
Ω, 5W resistor (such as Curtis p/n
MP-2) can be used across the contactor to precharge the capacitors and reduce
the inrush current through the contacts.
In compound motor applications, the main contactor driver is used to
drive the shunt field. The main contactor—if one is used—is normally con
-
nected directly to B- in this configuration.
Forward/Reverse Contactors
For forward/reverse, a paired single-pole, double-throw (2×SPDT) contactor
is recommended, such as an Albright DC88 or DC182
. With 4-terminal split
field motors, two single-pole, single-throw (SPST) contactors are typically used.
The coil voltage should match the vehicle voltage. The maximum allowed coil
current is 1 ampere.
Forward/Reverse, Emergency Reverse, and Mode Switches
These input switches can be any type of single-pole, single-throw (SPST) switch
capable of switching the battery voltage at 10 mA.
Circuitry Protection Devices
For reverse polarity protection, a diode should be added to the control circuit.
It must be sized appropriately for the maximum contactor coil currents (and
shunt current, in compound motor applications). To protect the control wiring
from accidental shorts, a low current fuse (appropriate for the maximum cur-
rent draw) should be connected in series with the battery feed. These devices
are both shown in the wiring diagrams.
2 — INSTALLATION & WIRING
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