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On the end of the switch, an adjustable screw can be seen. Turning the screw “IN” or
“CLOCKWISE” will increase the pressure at which the contact opens. Turning the screw
“OUT” or “COUNTER-CLOCKWISE” will reduce the pressure at which the contact opens.
Typically, the contact will open at about 75-100 psi.
To test the switch on-site, place the leads of a VOM test meter directly on the solenoid and
across the two DOWN direction solenoid connections. Set the meter on low voltage direct
current setting. With the lift operating in the DOWN direction, the meter should read
approximately 24 Volts DC, because the solenoid is now energized.
Stop the lift, and close the gate valve with the yellow handle. Attempt to run the lift in the
DOWN direction either by placing a call or by using temporary buttons or by placing a jumper
between connections number two and four (2 and 4) on the controller PC board.
If the gauge isolating valve is open, the pressure gauge should be reading ZERO. The test
meter should read ZERO volts on the solenoid connections due to the contacts opening in the
negative pressure switch. If there is power on the connections, adjust the switch as instructed.
SEQUENCE OF OPERATION OF THE EPV VALVE
When a button is pressed to call or send the lift in the UP direction, power is applied to the
Valve PC board and the microprocessor. The EPV solenoid is fully closed before the power is
applied. On application of power, however, the solenoid opens fully for a short period (about
one second), when all the oil sent from the pump bypasses back to the oil reservoir. This
permits the motor to start up under very little load. This start time is adjusted by means of the
“F0” function. This FUNCTION can be seen on the valve PC board electronic display as “F0”,
which stands for “FUNCTION 0”. The microprocessor continues to send signals to the EPV
solenoid in accordance with the “F0” settings. When the timing of the “F0” setting has passed,
the display changes to the “F1” setting and the lift smoothly accelerates. The display then
changes to the “F3” setting, which is the “FULL SPEED UP” setting. This move from “F0” to
“F3” can be observed at the Valve PC board LED display, as it occurs.
When the elevator reaches its selected floor, the binary cam (or vane) at that floor will send a
signal to the controller that the elevator is at the correct floor, as the processor starts the
“DECELERATION” phase to the floor level. The display will indicate a change from “F3” back
to “F1”, and the lift will immediately start to slow down, as the solenoid responds to the new
signal. The slowdown distance from full speed to leveling speed is approximately 5" to 5 1/2".
(The distance depends on cam or vane length and both vary depending on speed). As the lift
approaches within a few inches of the floor level, the display will change from “F1” to “F2”,
indicating the “UP LEVELING” mode. The processor will send a signal to the EPV solenoid
and will instruct it to open to the appropriate setting for the “F2” function. The lift will slow to
the instructed “LEVELING SPEED” and will continue ascending until the “LU” switch or LED
comes off the leveling cam or the vane signal. The lift will then “STOP”, as instructed.
The process for the DOWN direction operation and speed signals is identical to the UP
direction, except that the FUNCTION numbers are different. For example, “F4” is the DOWN
acceleration and deceleration function; “F5” is the DOWN leveling function; and “F6” is the
DOWN Full Speed function.
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