Klixon 7235 and 7236 overload sensing controls are designed for the remote sensing of overloads in aircraft electrical systems or other applicable remote systems. They are for the protection of 28 VDC circuits or for 120 VAC single–phase or three–phase circuits operating at 60 to 1000 Hz.

For three–phase AC circuit protection, a 28 VDC control circuit is required.

One three–phase relay or three single–phase relays with their coils wired in series may be used in the control circuit. With either arrangement, all three phases will trip open simultaneously when an overload exists in any one phase.

Klixon overload sensing controls consist of a bi-metal thermal actuating disc in series with the load terminals and an auxiliary single–phase, double–throw switch fitted to the main base forming a compact vibration–proof construction. The aircraft relay is wired in series with the sensing control through the S2 terminal of the auxiliary switch.

When the control senses and overload, the Klixon disc operates the auxiliary switch, breaking circuit S1-S2 and making circuit S1-S3. This opens the relay, thus opening the load circuit.

Using With 3MC Breakers
If the 3MC circuit breaker is to be used in the circuit, a suitable resistance (R1) must be built into the sensing control in order to limit the current flow through the manual control when the auxiliary switch moves to the S3 position. In applications where the 3MC will not be used this resistance is not necessary. In such an instance, the circuit through the S3 terminal may be used to trigger a signal lamp or some other device. For example, in applications using a mechanically latched–in relay the circuit through S3 may be used to release the relay magnetically which, in turn, opens the load circuit. In this application the control circuit through S2 could be used in conjunction with a momentary contact switch to energize the pull–in coil of the relay.

1.52mm (0.06") total excursion, 10–55 cps

25G

10G

3 cycles at 100 amps

Corrosion: 15 hours (QQ-M-151A)
Sand and dust: 4 hours

Relay capacity: 5 cycles, 20 VDC, 40,000 ft alt.

7–50 amps: 2,000 amp adjusted circuit
Over 50 amps: 4,000 amp adjusted circuit

Rating (in amps)

7–125

7–125

150–400

150–400

0.75 ohm

None

0.75 ohm

None

3 amps

10 amps

3 amps

10 amps

10 amps

10 amps

10 amps

10 amps

7235

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7235-001

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7235-002

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7236

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