ATC-Automatic Timing & Control 305E Series Data Sheet

Motor-Driven Analog Reset Timer

ON DELAY

Timing Sequence**

SWITCH CONTACTS Before During End of
Start Cycle Cycle *

ELECTROMECHANICAL TIMER 305E Series

Instantaneous
14-10/6-7

Delayed (D2)
11-13

Delayed (D1)
4-3

* D2 trips approximately 1/2% of range after end of cycle.

** Assumes a sustained closed start signal (i.e. longer than the
dial set time).

OFF DELA

Timing S

SWITCH
Start Cycle Cycle *

Instantaneous
14-10/6-7

Delayed (D2)
11-13

Delayed (D
4-3

* D2 trips approximately 1/2% to 5% of range after end of cycle.

** Assumes a sustained closed start signal (i.e. longer than the
dial set time).

11-12

4-5

11-12

4-5

)

1

14-9/6-8

CTS

CONTA

14-9/6-8

Bef

ore

equence**

During

*

Y

*

End of

E24305

Noted for its circuit flexibility, the 305 also provides the highest
accuracy among analog timers. Available for either ON-Delay or OFF­Delay operation.

The 305 provides delay, interval or pulse timing function for up to
7 load circuits through two instantaneous and two delayed switches.
It features a plug-in design and cycle progress indication.

HIGHEST ACCURACY: Because of its exclusive infinite engagement
clutch, the 305 has a repeat accuracy of 0.2%, highest of any timer in
its class.

PLUG-IN AND DUST-TIGHT DESIGN: By virtue of its true plug-in design,
the body of a 305 can be replaced in seconds without disturbing the
housing or disconnecting the wiring. Its gasketed dial assembly forms a
dust-tight seal against the housing, whether panel or surface-mounted.

FASTEST RESET: All 305 timers reset to a full-scale setting within 0.1
second, proportionately faster for shorter settings.

CIRCUIT FLEXIBILITY: All the contacts of its two instantaneous and two
delayed load switches are externally accessible at a 14 point terminal
block.

LONGEST LIFE: With an average mechanical life expectancy of over
5,000,000 operations before the first failure, the 305 is the leader in
its class.

PILOT LIGHT: A built-in pilot light indicates that the timer is running.

OPERATION

The 305 is a synchronous motor-driven timer with an
electrically-operated clutch equipped either for ON-Delay or OFF-Delay
operation.

ON-DELAY: When power is applied (start signal on), the clutch solenoid
is energized. Two things happen immediately and simultaneously, the
instantaneous switches transfer from one set of contacts to the other,
and the motor begins to drive the cycle progress pointer toward zero.

At the end of the timed period, the pointer trips one of the delayed
switches, a brief time later (about 1/2% of full scale), the other delayed
switch is tripped, stopping the timer motor but leaving the clutch en­gaged. The timer does not reset until power to the clutch is removed.

OFF-DELAY: Timing starts when power is removed (star t signal off),
from the spring-loaded, normally engaged clutch. The timer is reset
when power is restored to the clutch solenoid; simultaneously, the
instantaneous contacts are tripped. Action of the delayed contacts is the
same as with ON-Delay timers. A power outage stops the motor but does
not reset the OFF-Delay 305E.

BLACK
Circuit Closed

GRAY
Circuit Open

Automatic Timing & Controls

WIRING

AC WIRING

TERMINAL WIRING

SPECIFICATIONSDIMENSIONS (INCHES/MILLIMETERS)

MODELS ON-Delay

OFF-Delay

RANGES (AC) 13 standard ranges, from 6 SEC to 60 HRS at
60 Hz.

REPEAT ACCURACY AC MODELS: – 0.2% of full scale (For ranges of
60 SEC or less, it may be necessary to run timer
motor before start to achieve related accuracy)

RESET TIME 0.1 SEC, full scale

MIN. SETTING 1/60th of range (all models except 0.3 SEC for

6 SEC model)

DIAL DIVISIONS 6 SEC, 60 SEC, 120 SEC, 240 SEC,
60 MIN, 240 MIN, 6 HR, and
60 HR =120 Dial Divisions
30 SEC, 15 MIN, 30 MIN, 15 HR.,
and 30 HR =150 Dial Divisions

LIFE EXPECTANCY MECHANICAL: over 5,000,000 operations
CONTACTS: 3,000,000 operations under
resistive or inductive load of 1A

TIMING MOTOR Synchronous, permanently lubricated

TIMING Single cycle interval or delay

LOAD SWITCHES INSTANTANEOUS: two, each SPDT; self cleaning,

heavy-duty silver contacts.
DELAYED: two, each SPDT; precision
type, silver contacts
CONTACT RATING (non-inductive):
10 amps, 120 VAC
5 amps, 240 VAC

PILOT LIGHT Wired in parallel with motor.

TERMINALS 14 screw terminals accessible at rear;

integral wiring diagram on timer housing.

HOUSING Plug-in design; completely gasketed,
dust-tight when surface or panel-mounted

POWER AC MODELS: 120, 60Hz (all ranges),
REQUIREMENTS (– 10%, - 10%)

AC MODELS: running current 0.128 A (115 VAC)
inrush current 0.628 A (115 VAC)

TEMPERATURE 32° to 140°F (0° to 60°C)
RATING

WEIGHT NET: 2 lb., 6 oz. SHIPPING: 2 lb., 12 oz.

MOUNTING STANDARD: Hardware is provided to mount timer
ACCESSORIES so that it is dust-tight from front of

panel.
OPTIONAL: Surface mounting with rear-facing
terminals. (See Accessories)

ELECTROMECHANICAL TIMER 305E Series

Automatic Timing & Controls